contrib change_prefix.sh: exit successfully

(cherry picked from commit 0a896b6b)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/change_prefix.sh

@@ -74,3 +74,5 @@ for file in `find . -type f`; do
     process "$file"
   fi
 done
+
+exit 0