make: include RIOT_VERSION in CFLAGS for riotbuild

fixes #5695

Makefile.include

@@ -508,13 +508,13 @@ $(RIOTBUILD_CONFIG_HEADER_C):
 	@mkdir -p '$(dir $@)'
 	$(AD)'$(RIOTBASE)/dist/tools/genconfigheader/genconfigheader.sh' '$@' $(CFLAGS_WITH_MACROS)
 
-CFLAGS_WITH_MACROS := $(CFLAGS)
-CFLAGS := $(patsubst -D%,,$(CFLAGS))
-CFLAGS := $(patsubst -U%,,$(CFLAGS))
-CFLAGS += -include '$(RIOTBUILD_CONFIG_HEADER_C)'
-
 ifneq (,$(RIOT_VERSION_OVERRIDE))
 export CFLAGS += -DRIOT_VERSION=\"$(RIOT_VERSION_OVERRIDE)\"
 else
 export CFLAGS += -DRIOT_VERSION=\"$(RIOT_VERSION)\"
 endif
+
+CFLAGS_WITH_MACROS := $(CFLAGS)
+CFLAGS := $(patsubst -D%,,$(CFLAGS))
+CFLAGS := $(patsubst -U%,,$(CFLAGS))
+CFLAGS += -include '$(RIOTBUILD_CONFIG_HEADER_C)'