Clean up lib dependencies

libzutil is currently statically linked into libzfs, libzfs_core and
libzpool. Avoid the unnecessary duplication by removing it from libzfs
and libzpool, and adding libzfs_core to libzpool.

Remove a few unnecessary dependencies:
- libuutil from libzfs_core
- libtirpc from libspl
- keep only libcrypto in libzfs, as we don't use any functions from
  libssl
- librt is only used for clock_gettime, however on modern systems that's
  in libc rather than librt. Add a configure check to see if we actually
  need librt
- libdl from raidz_test

Add a few missing dependencies:
- zlib to libefi and libzfs
- libuuid to zpool, and libuuid and libudev to zed
- libnvpair uses assertions, so add assert.c to provide aok and
  libspl_assertf

Sort the LDADD for programs so that libraries that satisfy dependencies
come at the end rather than the beginning of the linker command line.

Revamp the configure tests for libaries to use FIND_SYSTEM_LIBRARY
instead. This can take advantage of pkg-config, and it also avoids
polluting LIBS.

List all the required dependencies in the pkgconfig files, and move the
one for libzfs_core into the latter's directory. Install pkgconfig files
in $(libdir)/pkgconfig on linux and $(prefix)/libdata/pkgconfig on
FreeBSD, instead of /usr/share/pkgconfig, as the more correct location
for library .pc files.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10538

config/find_system_library.m4

@@ -11,7 +11,9 @@ AC_DEFUN([FIND_SYSTEM_LIBRARY], [
 
     _library_found=
 
-    PKG_CHECK_MODULES([$1], [$2], [_library_found=1], [
+    AS_IF([test -n "$2"], [PKG_CHECK_MODULES([$1], [$2], [_library_found=1], [:])])
+
+    AS_IF([test -z "$_library_found"], [
         AS_IF([test -f /usr/include/[$3]], [
             AC_SUBST([$1][_CFLAGS], [])
             AC_SUBST([$1][_LIBS], ["-l[$5]]")
@@ -21,6 +23,7 @@ AC_DEFUN([FIND_SYSTEM_LIBRARY], [
             AC_SUBST([$1][_LIBS], ["-L/usr/local -l[$5]]")
             _library_found=1
         ],[dnl ELSE
+	    :
             m4_foreach([prefix], [$4], [
                 AS_IF([test "x$_library_found" != "x1"], [
                     AS_IF([test -f [/usr/include/]prefix[/][$3]], [
@@ -37,7 +40,7 @@ AC_DEFUN([FIND_SYSTEM_LIBRARY], [
         ])])
 
         AS_IF([test -z "$_library_found"], [
-            AC_MSG_WARN([cannot find [$2] via pkg-config or in the standard locations])
+            AC_MSG_WARN([cannot find [$5] via pkg-config or in the standard locations])
         ])
     ])
 
@@ -51,7 +54,7 @@ AC_DEFUN([FIND_SYSTEM_LIBRARY], [
         LDFLAGS="$LDFLAGS $[$1][_LIBS]"
 
         AC_CHECK_HEADER([$3], [], [
-            AC_MSG_WARN([header [$3] for library [$2] is not usable])
+            AC_MSG_WARN([header [$3] for library [$5] is not usable])
             _library_found=
         ])
 
@@ -66,6 +69,7 @@ AC_DEFUN([FIND_SYSTEM_LIBRARY], [
     ])
 
     AS_IF([test -n "$_library_found"], [
+        AC_DEFINE([HAVE_][$1], [1], [Define if you have [$5]])
         :;$7
     ],[dnl ELSE
         :;$8

config/user-clock_gettime.m4

@@ -0,0 +1,12 @@
+dnl #
+dnl # Check if librt is required for clock_gettime.
+dnl # clock_gettime is generally available in libc on modern systems.
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_USER_CLOCK_GETTIME], [
+	AC_CHECK_FUNC([clock_gettime], [], [
+	    AC_CHECK_LIB([rt], [clock_gettime], [
+		AC_SUBST([LIBCLOCK_GETTIME], [-lrt])], [
+		AC_MSG_FAILURE([*** clock_gettime is missing in libc and librt])
+	    ])
+	])
+])

config/user-libaio.m4

@@ -2,13 +2,5 @@ dnl #
 dnl # Check for libaio - only used for libaiot test cases.
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBAIO], [
-	LIBAIO=
-
-	AC_CHECK_HEADER([libaio.h], [
-	    user_libaio=yes
-	    AC_SUBST([LIBAIO], ["-laio"])
-	    AC_DEFINE([HAVE_LIBAIO], 1, [Define if you have libaio])
-	], [
-	    user_libaio=no
-	])
+	FIND_SYSTEM_LIBRARY(LIBAIO, [], [libaio.h], [], [aio], [], [user_libaio=yes], [user_libaio=no])
 ])

config/user-libblkid.m4

@@ -3,11 +3,7 @@ dnl # Check for libblkid.  Basic support for detecting ZFS pools
 dnl # has existing in blkid since 2008.
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBBLKID], [
-	LIBBLKID=
-
-	AC_CHECK_HEADER([blkid/blkid.h], [], [AC_MSG_FAILURE([
-	*** blkid.h missing, libblkid-devel package required])])
-
-	AC_SUBST([LIBBLKID], ["-lblkid"])
-	AC_DEFINE([HAVE_LIBBLKID], 1, [Define if you have libblkid])
+	FIND_SYSTEM_LIBRARY(LIBBLKID, [blkid], [blkid/blkid.h], [], [blkid], [], [], [
+		AC_MSG_FAILURE([
+		*** blkid.h missing, libblkid-devel package required])])
 ])

config/user-libcrypto.m4

@@ -0,0 +1,8 @@
+dnl #
+dnl # Check for libcrypto. Used for userspace password derivation via PBKDF2.
+dnl #
+AC_DEFUN([ZFS_AC_CONFIG_USER_LIBCRYPTO], [
+	FIND_SYSTEM_LIBRARY(LIBCRYPTO, [libcrypto], [openssl/evp.h], [], [crypto], [PKCS5_PBKDF2_HMAC_SHA1], [], [
+		AC_MSG_FAILURE([
+		*** evp.h missing, libssl-devel package required])])
+])

config/user-libssl.m4

@@ -1,12 +0,0 @@
-dnl #
-dnl # Check for libssl. Used for userspace password derivation via PBKDF2.
-dnl #
-AC_DEFUN([ZFS_AC_CONFIG_USER_LIBSSL], [
-	LIBSSL=
-
-	AC_CHECK_HEADER([openssl/evp.h], [], [AC_MSG_FAILURE([
-	*** evp.h missing, libssl-devel package required])])
-
-	AC_SUBST([LIBSSL], ["-lssl -lcrypto"])
-	AC_DEFINE([HAVE_LIBSSL], 1, [Define if you have libssl])
-])

config/user-libudev.m4

@@ -2,18 +2,18 @@ dnl #
 dnl # Check for libudev - needed for vdev auto-online and auto-replace
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBUDEV], [
-	LIBUDEV=
+	FIND_SYSTEM_LIBRARY(LIBUDEV, [libudev], [libudev.h], [], [udev], [], [user_libudev=yes], [user_libudev=no])
 
-	AC_CHECK_HEADER([libudev.h], [
-	    user_libudev=yes
-	    AC_SUBST([LIBUDEV], ["-ludev"])
-	    AC_DEFINE([HAVE_LIBUDEV], 1, [Define if you have libudev])
-	], [
-	    user_libudev=no
+	AS_IF([test "x$user_libudev" = xyes], [
+	    AX_SAVE_FLAGS
+
+	    CFLAGS="$CFLAGS $LIBUDEV_CFLAGS"
+	    LDFLAGS="$LDFLAGS $LIBUDEV_LIBS"
+
+	    AC_CHECK_LIB([udev], [udev_device_get_is_initialized], [
+	        AC_DEFINE([HAVE_LIBUDEV_UDEV_DEVICE_GET_IS_INITIALIZED], 1, [
+	        Define if udev_device_get_is_initialized is available])], [])
+
+	    AX_RESTORE_FLAGS
 	])
-
-	AC_SEARCH_LIBS([udev_device_get_is_initialized], [udev], [
-	    AC_DEFINE([HAVE_LIBUDEV_UDEV_DEVICE_GET_IS_INITIALIZED], 1, [
-	    Define if udev_device_get_is_initialized is available])], [])
-
 ])

config/user-libuuid.m4

@@ -2,17 +2,7 @@ dnl #
 dnl # Check for libuuid
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBUUID], [
-	LIBUUID=
-
-	AC_CHECK_HEADER([uuid/uuid.h], [], [AC_MSG_FAILURE([
-	*** uuid/uuid.h missing, libuuid-devel package required])])
-
-	AC_SEARCH_LIBS([uuid_generate], [uuid], [], [AC_MSG_FAILURE([
-	*** uuid_generate() missing, libuuid-devel package required])])
-
-	AC_SEARCH_LIBS([uuid_is_null], [uuid], [], [AC_MSG_FAILURE([
-	*** uuid_is_null() missing, libuuid-devel package required])])
-
-	AC_SUBST([LIBUUID], ["-luuid"])
-	AC_DEFINE([HAVE_LIBUUID], 1, [Define if you have libuuid])
+	FIND_SYSTEM_LIBRARY(LIBUUID, [uuid], [uuid/uuid.h], [], [uuid], [uuid_generate, uuid_is_null], [], [
+	    AC_MSG_FAILURE([*** libuuid-devel package required])
+	])
 ])

config/user-zlib.m4

@@ -2,20 +2,7 @@ dnl #
 dnl # Check for zlib
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_ZLIB], [
-	ZLIB=
-
-	AC_CHECK_HEADER([zlib.h], [], [AC_MSG_FAILURE([
-	*** zlib.h missing, zlib-devel package required])])
-
-	AC_SEARCH_LIBS([compress2], [z], [], [AC_MSG_FAILURE([
-	*** compress2() missing, zlib-devel package required])])
-
-	AC_SEARCH_LIBS([uncompress], [z], [], [AC_MSG_FAILURE([
-	*** uncompress() missing, zlib-devel package required])])
-
-	AC_SEARCH_LIBS([crc32], [z], [], [AC_MSG_FAILURE([
-	*** crc32() missing, zlib-devel package required])])
-
-	AC_SUBST([ZLIB], ["-lz"])
-	AC_DEFINE([HAVE_ZLIB], 1, [Define if you have zlib])
+	FIND_SYSTEM_LIBRARY(ZLIB, [zlib], [zlib.h], [], [z], [compress2, uncompress, crc32], [], [
+	    AC_MSG_FAILURE([*** zlib-devel package required])
+	])
 ])

config/user.m4

@@ -6,6 +6,10 @@ AC_DEFUN([ZFS_AC_CONFIG_USER], [
 	ZFS_AC_CONFIG_USER_MOUNT_HELPER
 	ZFS_AC_CONFIG_USER_SYSVINIT
 	ZFS_AC_CONFIG_USER_DRACUT
+	AM_COND_IF([BUILD_FREEBSD], [
+		PKG_INSTALLDIR(['${prefix}/libdata/pkgconfig'])], [
+		PKG_INSTALLDIR
+	])
 	ZFS_AC_CONFIG_USER_ZLIB
 	AM_COND_IF([BUILD_LINUX], [
 		ZFS_AC_CONFIG_USER_UDEV
@@ -15,8 +19,9 @@ AC_DEFUN([ZFS_AC_CONFIG_USER], [
 	])
 	ZFS_AC_CONFIG_USER_LIBTIRPC
 	ZFS_AC_CONFIG_USER_LIBUDEV
-	ZFS_AC_CONFIG_USER_LIBSSL
+	ZFS_AC_CONFIG_USER_LIBCRYPTO
 	ZFS_AC_CONFIG_USER_LIBAIO
+	ZFS_AC_CONFIG_USER_CLOCK_GETTIME
 	ZFS_AC_CONFIG_USER_PAM
 	ZFS_AC_CONFIG_USER_RUNSTATEDIR
 	ZFS_AC_CONFIG_USER_MAKEDEV_IN_SYSMACROS