Build SF executable with USE_HWC2 when needed am: f9f7f6931f
am: 58719ff766

Change-Id: I559a674184a0a08829b49dd90d85e75478385021
diff --git a/services/surfaceflinger/Android.mk b/services/surfaceflinger/Android.mk
index 6a34898..08115ea 100644
--- a/services/surfaceflinger/Android.mk
+++ b/services/surfaceflinger/Android.mk
@@ -148,6 +148,10 @@
     LOCAL_CFLAGS += -DENABLE_CPUSETS
 endif
 
+ifeq ($(TARGET_USES_HWC2),true)
+    LOCAL_CFLAGS += -DUSE_HWC2
+endif
+
 LOCAL_SRC_FILES := \
     main_surfaceflinger.cpp