[tracker] tracker-extract-gstreamer: Prevent warning if there is no TOC

[Carlos Garnacho <carlosg src gnome org>]

commit 0c788328a17f8e381a30ad6bacca370c9fca05c4
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun May 8 23:20:06 2016 +0200

    tracker-extract-gstreamer: Prevent warning if there is no TOC
    
    Warning introduced in commit 99ab02a7. We should only attempt this
    TOC when there is one from gstreamer.

 src/tracker-extract/tracker-extract-gstreamer.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/tracker-extract/tracker-extract-gstreamer.c b/src/tracker-extract/tracker-extract-gstreamer.c
index bc5ee62..c2aef3d 100644
--- a/src/tracker-extract/tracker-extract-gstreamer.c
+++ b/src/tracker-extract/tracker-extract-gstreamer.c
@@ -1706,7 +1706,8 @@ tracker_extract_gstreamer (const gchar          *uri,
                        extractor->toc = tracker_cue_sheet_parse_uri (uri);
                }
 
-               if (extractor->toc == NULL) {
+               if (extractor->toc == NULL &&
+                   extractor->gst_toc != NULL) {
                        extractor->toc = translate_discoverer_toc (extractor->gst_toc);
                }