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/zinject/Makefile.am

@@ -1,16 +1,12 @@
-include $(top_srcdir)/config/Rules.am
-
-sbin_PROGRAMS = zinject
+sbin_PROGRAMS   += zinject
+CPPCHECKTARGETS += zinject
 
 zinject_SOURCES = \
-	translate.c \
-	zinject.c \
-	zinject.h
+	%D%/translate.c \
+	%D%/zinject.c \
+	%D%/zinject.h
 
 zinject_LDADD = \
-	$(abs_top_builddir)/libzfs.la \
-	$(abs_top_builddir)/libzfs_core.la \
-	$(abs_top_builddir)/libnvpair.la
-
-include $(top_srcdir)/config/CppCheck.am
-CPPCHECKTARGETS += zinject
+	libzfs.la \
+	libzfs_core.la \
+	libnvpair.la