Merge pull request #823 from douglas-raillard-arm/dr/add_fno_builtin

Add -fno-builtin to CFLAGS

Makefile

@@ -149,7 +149,7 @@ ASFLAGS			+=	$(CPPFLAGS) $(ASFLAGS_$(ARCH))			\
 				-D__ASSEMBLY__ -ffreestanding 			\
 				-Wa,--fatal-warnings
 TF_CFLAGS		+=	$(CPPFLAGS) $(TF_CFLAGS_$(ARCH))		\
-				-ffreestanding -Wall -std=c99 -Os		\
+				-ffreestanding -fno-builtin -Wall -std=c99 -Os	\
 				-ffunction-sections -fdata-sections
 
 LDFLAGS			+=	--fatal-warnings -O1