[gnome-photos] Update to latest libgd

[Debarshi Ray <debarshir src gnome org>]

commit b8b1f81182ca4c9db2574fd330fc9dae40dbfa59
Author: Debarshi Ray <debarshir gnome org>
Date:   Sat Mar 4 08:34:22 2017 +0100

    Update to latest libgd
    
    GdMainBox::selection-changed is now emitted only after the list of
    selected child widgets is updated in case a selected GdMainBoxItem was
    removed. This prevents the following CRITICALs when deleting an item
    from the selection mode:
      CRITICAL **: photos_base_item_can_trash: assertion
        'PHOTOS_IS_BASE_ITEM (self)' failed
      CRITICAL **: photos_base_item_get_default_app_name: assertion
        'PHOTOS_IS_BASE_ITEM (self)' failed
    
    https://bugzilla.gnome.org/show_bug.cgi?id=779589

 libgd |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgd b/libgd
index eaef0ee..a4928d0 160000
--- a/libgd
+++ b/libgd
@@ -1 +1 @@
-Subproject commit eaef0ee3c2da2aa9b37f7a4ad0ffd5b2d1cae900
+Subproject commit a4928d0f5e7aebe7d0670fb65d5b6c1bcbe5dd60