rhel: Fix use of $< in ordinary Make rules.

POSIX only allows $< in inference rules, so avoid it for these target
rules.

Also, add a header to the generated spec files to remind developers that
they are generated.

Makefile.am

@@ -82,6 +82,7 @@ EXTRA_DIST += \
 	soexpand.pl
 
 ro_c = echo '/* -*- mode: c; buffer-read-only: t -*- */'
+ro_shell = printf '\043 Generated automatically -- do not modify!    -*- buffer-read-only: t -*-\n'
 
 SUFFIXES += .in
 .in:

rhel/automake.mk

@@ -20,11 +20,13 @@ EXTRA_DIST += \
 
 
 $(srcdir)/rhel/openvswitch-kmod-rhel5.spec: rhel/openvswitch-kmod-rhel5.spec.in $(top_builddir)/config.status
-	sed -e 's,[@]VERSION[@],$(VERSION),g' < $< > $@
+	($(ro_shell) && sed -e 's,[@]VERSION[@],$(VERSION),g') \
+		< $(srcdir)/rhel/openvswitch-kmod-rhel5.spec.in > $@
 
 $(srcdir)/rhel/openvswitch-kmod-rhel6.spec: rhel/openvswitch-kmod-rhel6.spec.in $(top_builddir)/config.status
-
-	sed -e 's,[@]VERSION[@],$(VERSION),g' < $< > $@
+	($(ro_shell) && sed -e 's,[@]VERSION[@],$(VERSION),g') \
+		< $(srcdir)/rhel/openvswitch-kmod-rhel6.spec.in > $@
 
 $(srcdir)/rhel/openvswitch.spec: rhel/openvswitch.spec.in $(top_builddir)/config.status
-	sed -e 's,[@]VERSION[@],$(VERSION),g' < $< > $@
+	($(ro_shell) && sed -e 's,[@]VERSION[@],$(VERSION),g') \
+		< $(srcdir)/rhel/openvswitch.spec.in > $@