[gnome-panel] clock: fix constness warning in clock-map.c

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 92a4436ec4f331cca1ed923e321e65956565cacd
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Oct 30 22:01:43 2016 +0200

    clock: fix constness warning in clock-map.c

 applets/clock/clock-map.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/applets/clock/clock-map.c b/applets/clock/clock-map.c
index 14e046e..fd6fe0e 100644
--- a/applets/clock/clock-map.c
+++ b/applets/clock/clock-map.c
@@ -28,7 +28,7 @@ enum {
         MARKER_NB
 };
 
-static char *marker_files[MARKER_NB] = {
+static const gchar *marker_files[MARKER_NB] = {
         "clock-map-location-marker.png",
         "clock-map-location-hilight.png",
         "clock-map-location-current.png"