Build rules for Renderscript compatibility library.

Bug: 7419958
Change-Id: I2e0f0bb632e6ff22b2cf1a1b96b28364637995cc
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 853f9a0..a566768 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -110,6 +110,7 @@
 LOCAL_RENDERSCRIPT_INCLUDES:=
 LOCAL_RENDERSCRIPT_INCLUDES_OVERRIDE:=
 LOCAL_RENDERSCRIPT_CC:=
+LOCAL_RENDERSCRIPT_COMPATIBILITY:=
 LOCAL_RENDERSCRIPT_FLAGS:=
 LOCAL_RENDERSCRIPT_TARGET_API:=
 LOCAL_BUILD_HOST_DEX:=