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

etc/zfs/Makefile.am

@@ -1,7 +1,7 @@
 pkgsysconfdir = $(sysconfdir)/zfs
 initconfdir = $(DEFAULT_INITCONF_DIR)
 
-pkgsysconf_DATA = \
+dist_pkgsysconf_DATA = \
 	vdev_id.conf.alias.example \
 	vdev_id.conf.sas_direct.example \
 	vdev_id.conf.sas_switch.example \
@@ -10,26 +10,13 @@ pkgsysconf_DATA = \
 pkgsysconf_SCRIPTS = \
 	zfs-functions
 
-EXTRA_DIST = $(pkgsysconf_DATA) \
-	zfs-functions.in
+EXTRA_DIST = zfs-functions.in
 
 $(pkgsysconf_SCRIPTS):%:%.in Makefile
-	-(if [ -e /etc/debian_version ]; then \
-		NFS_SRV=nfs-kernel-server; \
-	  else \
-		NFS_SRV=nfs; \
-	  fi; \
-	  if [ -e /sbin/openrc-run ]; then \
-		SHELL=/sbin/openrc-run; \
-	  else \
-		SHELL=/bin/sh; \
-	  fi; \
-	  $(SED) \
+	  -$(SED) \
 		 -e 's,@sbindir\@,$(sbindir),g' \
 		 -e 's,@sysconfdir\@,$(sysconfdir),g' \
 		 -e 's,@initconfdir\@,$(initconfdir),g' \
-		 $< >'$@'; \
-	  [ '$@' = 'zfs-functions' ] || \
-		chmod +x '$@')
+		 $< >'$@'
 
 CLEANFILES = $(pkgsysconf_SCRIPTS)