also call gst_deinit() in media-check and transcoding

More valgrind friendly.

validate/tools/gst-validate-media-check.c

@@ -132,6 +132,7 @@ main (int argc, gchar ** argv)
     gst_object_unref (reference);
   gst_object_unref (writer);
   gst_object_unref (runner);
+  gst_deinit ();
 
   return ret;
 }

validate/tools/gst-validate-transcoding.c

@@ -957,6 +957,7 @@ exit:
 #ifdef G_OS_UNIX
   g_source_remove (signal_watch_id);
 #endif
+  gst_deinit ();
 
   g_print ("\n=======> Test %s (Return value: %i)\n\n",
       ret == 0 ? "PASSED" : "FAILED", ret);