[gnome-sdk-images] Bump to lastest freedesktop-sdk-images

[Alexander Larsson <alexl src gnome org>]

commit a7d61d811e13d8a101944ac8bc769f634bfdf45e
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Sep 16 15:51:19 2015 +0200

    Bump to lastest freedesktop-sdk-images

 freedesktop-sdk-images |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/freedesktop-sdk-images b/freedesktop-sdk-images
index 1301dd9..6b6f15b 160000
--- a/freedesktop-sdk-images
+++ b/freedesktop-sdk-images
@@ -1 +1 @@
-Subproject commit 1301dd91db8b2b05f34995c380cb215bcb5b786e
+Subproject commit 6b6f15b9730e0193de6cdfee72aedd5e523b2931