MLBuild: release tag check on current hash

The tag check done when building for release should be done on the
current hash, and not medialibrary hash which is kept for local builds

buildsystem/compile-medialibrary.sh

@@ -137,7 +137,7 @@ fi
 cd ${MEDIALIBRARY_BUILD_DIR}
 
 if [ "$RELEASE" = "1" ]; then
-    git describe --exact-match --tags ${MEDIALIBRARY_HASH} > /dev/null || \
+    git describe --exact-match HEAD > /dev/null || \
         avlc_checkfail "Release builds must use tags"
 fi