kbuild: enable 'make CFLAGS=...' to add additional options to CC

The variable CFLAGS is a wellknown variable and the usage by
kbuild may result in unexpected behaviour.
On top of that several people over time has asked for a way to
pass in additional flags to gcc.

This patch replace use of CFLAGS with KBUILD_CFLAGS all over the
tree and enabling one to use:
make CFLAGS=...
to specify additional gcc commandline options.

One usecase is when trying to find gcc bugs but other
use cases has been requested too.

Patch was tested on following architectures:
alpha, arm, i386, x86_64, mips, sparc, sparc64, ia64, m68k

Test was simple to do a defconfig build, apply the patch and check
that nothing got rebuild.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/blackfin/Makefile b/arch/blackfin/Makefile
index 20841663270f..52a6ac072851 100644
--- a/arch/blackfin/Makefile
+++ b/arch/blackfin/Makefile
@@ -53,7 +53,7 @@ rev-$(CONFIG_BF_REV_0_5)  := 0.5
 rev-$(CONFIG_BF_REV_NONE) := none
 rev-$(CONFIG_BF_REV_ANY)  := any
 
-CFLAGS += -mcpu=$(cpu-y)-$(rev-y)
+KBUILD_CFLAGS += -mcpu=$(cpu-y)-$(rev-y)
 AFLAGS += -mcpu=$(cpu-y)-$(rev-y)
 
 head-y   := arch/$(ARCH)/mach-$(MACHINE)/head.o arch/$(ARCH)/kernel/init_task.o