Turn shellcheck into a normal make target. Fix new files it caught

This checks every file it checked (and a few more),
but explicitly instead of "if it works it works" best-effort
(which wasn't that good anyway)

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #10512
Closes #12101

contrib/dracut/02zfsexpandknowledge/Makefile.am

@@ -1,4 +1,5 @@
 include $(top_srcdir)/config/Substfiles.am
+include $(top_srcdir)/config/Shellcheck.am
 
 pkgdracutdir = $(dracutdir)/modules.d/02zfsexpandknowledge
 pkgdracut_SCRIPTS = \

contrib/dracut/90zfs/Makefile.am

@@ -1,4 +1,5 @@
 include $(top_srcdir)/config/Substfiles.am
+include $(top_srcdir)/config/Shellcheck.am
 
 pkgdracutdir = $(dracutdir)/modules.d/90zfs
 pkgdracut_SCRIPTS = \

contrib/dracut/90zfs/module-setup.sh.in

@@ -60,7 +60,7 @@ install() {
 	# shellcheck disable=SC2050
 	if [ @LIBFETCH_DYNAMIC@ != 0 ]; then
 		for d in $libdirs; do
-			[ -e "$d"/@LIBFETCH_SONAME@ ] && dracut_install "$d"/@LIBFETCH_SONAME@
+			[ -e "$d/"@LIBFETCH_SONAME@ ] && dracut_install "$d/"@LIBFETCH_SONAME@
 		done
 	fi
 	dracut_install @mounthelperdir@/mount.zfs

contrib/dracut/Makefile.am

@@ -1,3 +1,6 @@
+include $(top_srcdir)/config/Shellcheck.am
+
 SUBDIRS = 02zfsexpandknowledge 90zfs
+SHELLCHECKDIRS = $(SUBDIRS)
 
 EXTRA_DIST = README.dracut.markdown