fix git version flag

Makefile

@@ -3,7 +3,7 @@ WANT_ZIP=0
 TARGET_NAME := race
 GIT_VERSION := " $(shell git rev-parse --short HEAD || echo unknown)"
 ifneq ($(GIT_VERSION)," unknown")
-	CXXFLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
+	FLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
 endif
 
 ifeq ($(platform),)