[gnome-documents] build: Update to latest libgd

[Debarshi Ray <debarshir src gnome org>]

commit 67ca0278d5a6d70c055344b503c35a10452d1f45
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Sep 1 09:13:31 2015 +0200

    build: Update to latest libgd
    
    Fixes GdTaggedEntry theming and drops a deprecated property.

 libgd |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgd b/libgd
index 04b2480..7e0dd4b 160000
--- a/libgd
+++ b/libgd
@@ -1 +1 @@
-Subproject commit 04b2480259769709ec34d7ee48294878c94bbbb5
+Subproject commit 7e0dd4b15ea80673f62249ac092763b10fc226ad