Fix "file is executable, but no shebang" warnings

Fedora 28's RPM build checks warn when executable files don't have a
shebang line.  These warnings are caused when we (incorrectly)
include data & config files in the_SCRIPTS automake lines. Files in
_SCRIPTS are marked executable by automake. This patch fixes the
issue by including non-executable scripts in a _DATA line instead.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #7359 
Closes #7395

contrib/initramfs/scripts/Makefile.am

@@ -1,6 +1,6 @@
 scriptsdir = $(datarootdir)/initramfs-tools/scripts
 
-scripts_SCRIPTS = \
+scripts_DATA = \
 	zfs
 
 SUBDIRS = local-top
@@ -8,7 +8,7 @@ SUBDIRS = local-top
 EXTRA_DIST = \
 	$(top_srcdir)/contrib/initramfs/scripts/zfs.in
 
-$(scripts_SCRIPTS):%:%.in
+$(scripts_DATA):%:%.in
 	-$(SED) -e 's,@sbindir\@,$(sbindir),g' \
 		-e 's,@sysconfdir\@,$(sysconfdir),g' \
 		$< >'$@'