Update LayoutLib API level to 12.

Change-Id: I7e392515939728251424d44d5957f95bdf3eb741
diff --git a/sdk/platform_source.prop_template b/sdk/platform_source.prop_template
index e0832f4..9c4705c 100644
--- a/sdk/platform_source.prop_template
+++ b/sdk/platform_source.prop_template
@@ -5,6 +5,6 @@
 Pkg.Revision=1
 AndroidVersion.ApiLevel=${PLATFORM_SDK_VERSION}
 AndroidVersion.CodeName=${PLATFORM_VERSION_CODENAME}
-Layoutlib.Api=10
+Layoutlib.Api=12
 Layoutlib.Revision=1
 Platform.MinToolsRev=22