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/ia64/Makefile b/arch/ia64/Makefile
index 21033ed83307..9708a29c70b5 100644
--- a/arch/ia64/Makefile
+++ b/arch/ia64/Makefile
@@ -44,7 +44,7 @@ ifeq ($(call cc-version),0304)
         cflags-$(CONFIG_MCKINLEY)       += -mtune=mckinley
 endif
 
-CFLAGS += $(cflags-y)
+KBUILD_CFLAGS += $(cflags-y)
 head-y := arch/ia64/kernel/head.o arch/ia64/kernel/init_task.o
 
 libs-y                          += arch/ia64/lib/