[gnome-sdk-images] Use librsvg 2.40 branch (no rust dependency)

[Alexander Larsson <alexl src gnome org>]

commit 726be5ca326aa35255af58679b9ffbc4dd37354c
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Jan 18 18:11:36 2017 +0100

    Use librsvg 2.40 branch (no rust dependency)
    
    We don't have a rust compiler yet, so at least get this building
    again.

 org.gnome.Sdk.json.in |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 5b28245..f38647a 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -311,7 +311,8 @@
             "sources": [
                 {
                     "type": "git",
-                    "url": "git://git.gnome.org/librsvg"
+                    "url": "git://git.gnome.org/librsvg",
+                    "branch": "librsvg-2-40"
                 }
             ]
         },