Build: exclude -c flag from TF_CFLAGS

The -c flag should not be included in the global variable TF_CFLAGS;
it should be specified in the build rule only when its target is a
*.o file.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -149,7 +149,7 @@ ASFLAGS			+= 	-nostdinc -ffreestanding -Wa,--fatal-warnings	\
 				${DEFINES} ${INCLUDES}
 TF_CFLAGS		+= 	-nostdinc -ffreestanding -Wall			\
 				-Werror -Wmissing-include-dirs			\
-				-std=c99 -c -Os					\
+				-std=c99 -Os					\
 				$(TF_CFLAGS_$(ARCH))				\
 				${DEFINES} ${INCLUDES}
 TF_CFLAGS		+=	-ffunction-sections -fdata-sections

make_helpers/build_macros.mk

@@ -358,7 +358,7 @@ ifdef MAKE_BUILD_STRINGS
 else
 	@echo 'const char build_message[] = "Built : "$(BUILD_MESSAGE_TIMESTAMP); \
 	       const char version_string[] = "${VERSION_STRING}";' | \
-		$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -xc - -o $(BUILD_DIR)/build_message.o
+		$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -xc -c - -o $(BUILD_DIR)/build_message.o
 endif
 	$$(Q)$$(LD) -o $$@ $$(LDFLAGS) -Map=$(MAPFILE) --script $(LINKERFILE) \
 					$(BUILD_DIR)/build_message.o $(OBJS)

make_helpers/windows.mk

@@ -104,6 +104,6 @@ BUILT_TIME_DATE_STRING = const char build_message[] = "Built : "${BUILD_MESSAGE_
 VERSION_STRING_MESSAGE = const char version_string[] = "${VERSION_STRING}";
 define MAKE_BUILD_STRINGS
 	@echo $$(BUILT_TIME_DATE_STRING) $$(VERSION_STRING_MESSAGE) | \
-		$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -x c - -o $1
+		$$(CC) $$(TF_CFLAGS) $$(CFLAGS) -x c -c - -o $1
 endef