tools cpupower bench: Override CFLAGS assignments

Allow user to specify outside CFLAGS values as make argument

Corrects an issue where CFLAGS is passed as a make argument for
cpupower, but bench's makefile does not inherit and append to them.
Signed-off-by: Stanley Chan <schan@cloudflare.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/bench/Makefile

@@ -15,7 +15,7 @@ LIBS = -L../ -L$(OUTPUT) -lm -lcpupower
 OBJS = $(OUTPUT)main.o $(OUTPUT)parse.o $(OUTPUT)system.o $(OUTPUT)benchmark.o
 endif
 
-CFLAGS += -D_GNU_SOURCE -I../lib -DDEFAULT_CONFIG_FILE=\"$(confdir)/cpufreq-bench.conf\"
+override CFLAGS += -D_GNU_SOURCE -I../lib -DDEFAULT_CONFIG_FILE=\"$(confdir)/cpufreq-bench.conf\"
 
 $(OUTPUT)%.o : %.c
 	$(ECHO) "  CC      " $@