[gnome-boxes] Update libgd submodule

[Christophe Fergeau <teuf src gnome org>]

commit c43a4fb6272c5c4aa232baab11a519ac80cc964c
Author: Christophe Fergeau <cfergeau redhat com>
Date:   Mon Sep 3 17:22:30 2012 +0200

    Update libgd submodule
    
    This gives us a few selection mode improvements, and fixes make
    distcheck by avoiding constant rebuilds of libgd.vapi.

 libgd |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgd b/libgd
index 8d5897b..16cc32d 160000
--- a/libgd
+++ b/libgd
@@ -1 +1 @@
-Subproject commit 8d5897beae054b0ad21ab638260d7f71c5b357a6
+Subproject commit 16cc32dd2d6837d24efcf16d3af94a9ac53172ff