[gnome-music] Update to latest libgd

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit 7bd25dba6339347e0f32abfeb26d2784e77eb64a
Author: Vadim Rutkovsky <vrutkovs redhat com>
Date:   Tue Sep 1 12:03:01 2015 +0200

    Update to latest libgd
    
    https://bugzilla.gnome.org/show_bug.cgi?id=738516

 libgd |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgd b/libgd
index 8af0b5d..7e0dd4b 160000
--- a/libgd
+++ b/libgd
@@ -1 +1 @@
-Subproject commit 8af0b5d665b309c455b7d337f36e258f253bd599
+Subproject commit 7e0dd4b15ea80673f62249ac092763b10fc226ad