zoul: only pass -DDATE on platform.o
The other files do not need this definition.
@@ -20,7 +20,10 @@ BSL_SPEED ?= 460800
# Works in Linux and probably on OSX too (RTCC example)
COMPILE_DATE := $(shell date +"%02u %02d %02m %02y %02H %02M %02S")
-CFLAGS += -DDATE="\"$(COMPILE_DATE)\""
+CFLAGS_DATE ?= -DDATE="\"$(COMPILE_DATE)\""
+
+# Compile platform.o with -DDATE, other files without it.
+$(OBJECTDIR)/platform.o: CFLAGS += $(CFLAGS_DATE)
### Configure the build for the board and pull in board-specific sources
CONTIKI_TARGET_DIRS += . dev
