SDK: generate support library package on build server.

Also fix packaging of system image (it had an extra root
directory in it, e.g. it was packaging android-4/armeabi-v7a/
instead of just armeabu-v7a/)

Change-Id: I0254b2680168d25103222f8871b2af37a7406b58
diff --git a/sdk/support_source.properties b/sdk/support_source.properties
index cd3a0b0..16d5cd8 100644
--- a/sdk/support_source.properties
+++ b/sdk/support_source.properties
@@ -1,4 +1,6 @@
 Pkg.UserSrc=false
 Pkg.Revision=4
+Extra.Vendor=android
+Extra.Path=support
 Extra.OldPaths=compatibility