JNI does not use hwui_flags but LOCAL_CFLAGS

Test: Manual
Change-Id: I109cb9dbce61079d2aa8d313b88f45e882ed9254
diff --git a/core/jni/Android.mk b/core/jni/Android.mk
index a7b0fe9..65142ab 100644
--- a/core/jni/Android.mk
+++ b/core/jni/Android.mk
@@ -24,7 +24,7 @@
 # TODO: The final test should be:
 # TODO: ifneq ($(TARGET_ENABLE_LINEAR_BLENDING),false)
 ifeq ($(TARGET_ENABLE_LINEAR_BLENDING),true)
-    hwui_cflags += -DANDROID_ENABLE_LINEAR_BLENDING
+    LOCAL_CFLAGS += -DANDROID_ENABLE_LINEAR_BLENDING
 endif
 
 LOCAL_CFLAGS += -DGL_GLEXT_PROTOTYPES -DEGL_EGLEXT_PROTOTYPES