package.bbclass: Ensure we tell rpmdeps where to find its magic file

Without this, if rpmddeps came from a sstate package which was relocated it might not find its magic file and if that happens, requires/provides in packages could get corrupted. This leads to failures at rootfs time during builds with messages like:

libdbus-1.so.3 is needed by libdbus-glib-1-2-0.92-r1.armv5te

since the provides would be missing in the dbus package.

---

index d01275f..6775fda 100644
@@ -1110,7 +1110,7 @@ if [ x"$D" = "x" ]; then
 fi
 }
 
-RPMDEPS = "${STAGING_LIBDIR_NATIVE}/rpm/bin/rpmdeps"
+RPMDEPS = "${STAGING_LIBDIR_NATIVE}/rpm/bin/rpmdeps  --define '_rpmfc_magic_path ${STAGING_DIR_NATIVE}/usr/share/misc/magic.mgc'"
 
 # Collect perfile run-time dependency metadata
 # Output: