rpm: Fix rpm usage of prelink on the target

RPM has the ability to validate files that have been prelinked, however
the necessary configuration and staging was not done properly.  Resolve
this issue by fixing the macro paths, providing the missing RPM macro,
and correcting a defect in the way the prelink image class was working
with the necessary configuration file.

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>

meta/classes/image-prelink.bbclass

@@ -24,7 +24,7 @@ prelink_image () {
 	${STAGING_DIR_NATIVE}/usr/sbin/prelink --root ${IMAGE_ROOTFS} -amR
 
 	# Remove the prelink.conf if we had to add it.
-	if [ $dummy_prelink_conf ]; then
+	if [ "$dummy_prelink_conf" == "true" ]; then
 		rm -f ${IMAGE_ROOTFS}/etc/prelink.conf
 	fi