scenario: Add GST_VALIDATE_SCENARIOS_PATH environment variable

So you can specify the PATHS where to look for scenario files

validate/gst/validate/gst-validate-scenario.c

@@ -624,6 +624,7 @@ gst_validate_scenario_load (GstValidateScenario * scenario,
 {
   gboolean ret = TRUE;
   gchar *lfilename = NULL, *tldir = NULL;
+  const gchar *env_scenariodir = g_getenv ("GST_VALIDATE_SCENARIOS_PATH");
 
   if (!scenario_name)
     goto invalid_name;
@@ -637,6 +638,13 @@ gst_validate_scenario_load (GstValidateScenario * scenario,
     goto done;
   g_free (tldir);
 
+  if (env_scenariodir) {
+    tldir = g_build_filename (env_scenariodir, lfilename, NULL);
+    if ((ret = _load_scenario_file (scenario, tldir)))
+      goto done;
+    g_free (tldir);
+  }
+
   /* Try from local profiles */
   tldir =
       g_build_filename (g_get_user_data_dir (), "gstreamer-" GST_API_VERSION,