contrib/initramfs: switch to automake

Use automake to build initramfs scripts and hooks.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #6761

contrib/initramfs/hooks/Makefile.am

@@ -0,0 +1,20 @@
+hooksdir = $(datarootdir)/initramfs-tools/hooks
+
+hooks_SCRIPTS = \
+	zfs
+
+EXTRA_DIST = \
+	$(top_srcdir)/contrib/initramfs/hooks/zfs.in
+
+$(hooks_SCRIPTS):%:%.in
+	-$(SED) -e 's,@sbindir\@,$(sbindir),g' \
+		-e 's,@sysconfdir\@,$(sysconfdir),g' \
+		-e 's,@udevdir\@,$(udevdir),g' \
+		-e 's,@udevruledir\@,$(udevruledir),g' \
+		$< >'$@'
+
+clean-local::
+	-$(RM) $(hooks_SCRIPTS)
+
+distclean-local::
+	-$(RM) $(hooks_SCRIPTS)