Fixes for make dist

Reduce the usage of EXTRA_DIST. If files are conditionally included in
_SOURCES, _HEADERS etc, automake is smart enough to dist all files that
could possibly be included, but this does not apply to EXTRA_DIST,
resulting in make dist depending on the configuration.

Add some files that were missing altogether in various Makefile's.

The changes to disted files in this commit (excluding deleted files):

+./cmd/zed/agents/README.md
+./etc/init.d/README.md
+./lib/libspl/os/freebsd/getexecname.c
+./lib/libspl/os/freebsd/gethostid.c
+./lib/libspl/os/freebsd/getmntany.c
+./lib/libspl/os/freebsd/mnttab.c
-./lib/libzfs/libzfs_core.pc
-./lib/libzfs/libzfs.pc
+./lib/libzfs/os/freebsd/libzfs_compat.c
+./lib/libzfs/os/freebsd/libzfs_fsshare.c
+./lib/libzfs/os/freebsd/libzfs_ioctl_compat.c
+./lib/libzfs/os/freebsd/libzfs_zmount.c
+./lib/libzutil/os/freebsd/zutil_compat.c
+./lib/libzutil/os/freebsd/zutil_device_path_os.c
+./lib/libzutil/os/freebsd/zutil_import_os.c
+./module/lua/README.zfs
+./module/os/linux/spl/README.md
+./tests/README.md
+./tests/zfs-tests/tests/functional/cli_root/zfs_clone/zfs_clone_rm_nested.ksh
+./tests/zfs-tests/tests/functional/cli_root/zfs_send/zfs_send_encrypted_unloaded.ksh
+./tests/zfs-tests/tests/functional/inheritance/README.config
+./tests/zfs-tests/tests/functional/inheritance/README.state
+./tests/zfs-tests/tests/functional/rsend/rsend_016_neg.ksh
+./tests/zfs-tests/tests/perf/fio/sequential_readwrite.fio

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10501

config/kernel-acl-refcount.m4

@@ -1,20 +0,0 @@
-dnl #
-dnl # 4.16 kernel: check if struct posix_acl acl.a_refcount is a refcount_t.
-dnl # It's an atomic_t on older kernels.
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_ACL_HAS_REFCOUNT], [
-	AC_MSG_CHECKING([whether posix_acl has refcount_t])
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/backing-dev.h>
-		#include <linux/refcount.h>
-		#include <linux/posix_acl.h>
-	],[
-		struct posix_acl acl;
-		refcount_t *r __attribute__ ((unused)) = &acl.a_refcount;
-	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_ACL_REFCOUNT, 1, [posix_acl has refcount_t])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])