[gnome-sdk-images] Remove gstreamer 1.10 plugins before building 1.12

[Alexander Larsson <alexl src gnome org>]

commit 262a766675b020a5b1d46f28b852fa1b62b02845
Author: Alexander Larsson <alexl redhat com>
Date:   Mon Sep 18 11:58:30 2017 +0200

    Remove gstreamer 1.10 plugins before building 1.12

 org.gnome.Sdk.json.in |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 3c47700..a35f315 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -415,6 +415,10 @@
                     "type": "git",
                     "url": "https://anongit.freedesktop.org/git/gstreamer/gstreamer.git";
                 }
+            ],
+            "build-commands": [
+                /* We delete all the 1.10 plugins to avoid version mismatches with renamed or removed 
plugins */
+                "rm -rf /usr/lib/gstreamer-1.0"
             ]
         },
         {