Add flag indicating gpu support in emulator system image.

Change-Id: Ica0c02c4d65a3311254f3d46a71956044bf46b82
diff --git a/sdk/images_x86_source.prop_template b/sdk/images_x86_source.prop_template
index 62e2e0d..a587cd1 100644
--- a/sdk/images_x86_source.prop_template
+++ b/sdk/images_x86_source.prop_template
@@ -4,3 +4,4 @@
 AndroidVersion.ApiLevel=${PLATFORM_SDK_VERSION}
 AndroidVersion.CodeName=${PLATFORM_VERSION_CODENAME}
 SystemImage.Abi=x86
+SystemImage.GpuSupport=true