gps.c: Fixed a small memory leak

osm_gps_map_get_default_cache_directory() uses stdc:strdup to allocate
memory for the returned string. Lets try to free the memory
pointed by 'cachebasedir'.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

gps.c

@@ -187,6 +187,7 @@ OsmGpsMap *init_map(void)
 	osm_gps_map_layer_add(OSM_GPS_MAP(map), osd);
 	g_object_unref(G_OBJECT(osd));
 	free((void*)cachebasedir);
+	free((void*)cachedir);
 	return map;
 }