[tracker] libtracker-miner: Fix compile warning

[Carlos Garnacho <carlosg src gnome org>]

commit 22fc4b7d56f4e851042baaace1f4e1acc97f2d21
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Nov 25 23:03:49 2015 +0100

    libtracker-miner: Fix compile warning

 src/libtracker-miner/tracker-thumbnailer.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/libtracker-miner/tracker-thumbnailer.c b/src/libtracker-miner/tracker-thumbnailer.c
index bacf8a5..6b678a4 100644
--- a/src/libtracker-miner/tracker-thumbnailer.c
+++ b/src/libtracker-miner/tracker-thumbnailer.c
@@ -220,7 +220,7 @@ tracker_thumbnailer_initable_init (GInitable     *initable,
                        i = 0;
                        while (g_hash_table_iter_next (&iter, &key, &value)) {
                                private->supported_mime_types[i] = g_strdup (key);
-                               g_debug ("  %s", key);
+                               g_debug ("  %s", (gchar *) key);
                                i++;
                        }