[gnome-photos] Update to latest libgd

[Debarshi Ray <debarshir src gnome org>]

commit 9c79c0bc1d2306677dfea40218432d61b858d429
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Aug 1 15:14:32 2017 +0200

    Update to latest libgd
    
    Silences -Wparentheses and -Wunused-variable.

 libgd |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgd b/libgd
index 3b8e843..63d13ea 160000
--- a/libgd
+++ b/libgd
@@ -1 +1 @@
-Subproject commit 3b8e843d841b4a7236c2a8f21c164b0d2a616400
+Subproject commit 63d13ea49990ac23a214acc4f8a7c0d8b0405cfd