autoconf: use include directives instead of recursing down cmd

No installation diff, dist lost
  -zfs-2.1.99/cmd/fsck_zfs/fsck.zfs
which was distributed erroneously, since it's generated

Also clean gitrev on clean

Also add -e 'any possible bashisms' to default checkbashisms flags,
and fully parallelise it and shellcheck, and it works out-of-tree, too

Also align the Release in the dist META file correctly

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13316

cmd/mount_zfs/.gitignore

@@ -1 +0,0 @@
-mount.zfs

cmd/mount_zfs/Makefile.am

@@ -1,23 +1,20 @@
-include $(top_srcdir)/config/Rules.am
-
 #
 # Ignore the prefix for the mount helper.  It must be installed in /sbin/
 # because this path is hardcoded in the mount(8) for security reasons.
 # However, if needed, the configure option --with-mounthelperdir= can be used
 # to override the default install location.
 #
-sbindir=$(mounthelperdir)
-sbin_PROGRAMS = mount.zfs
+mounthelper_PROGRAMS += mount.zfs
+CPPCHECKTARGETS      += mount.zfs
 
 mount_zfs_SOURCES = \
-	mount_zfs.c
+	%D%/mount_zfs.c
 
 mount_zfs_LDADD = \
-	$(abs_top_builddir)/libzfs.la \
-	$(abs_top_builddir)/libzfs_core.la \
-	$(abs_top_builddir)/libnvpair.la
+	libzfs.la \
+	libzfs_core.la \
+	libnvpair.la
 
 mount_zfs_LDADD += $(LTLIBINTL)
 
-include $(top_srcdir)/config/CppCheck.am
-CPPCHECKTARGETS += mount.zfs
+CPPCHECKTARGETS += raidz_test