[PATCH] kbuild: fix W=1 with gcc 4.3.2

[Sam Ravnborg <sam@ravnborg.org>]

Building a kernel using W=1 with gcc 4.3.2 failed like this:

    cc1: error: unrecognized command line option "-Wpacked-bitfield-compat"

Make use of this option dependent on the compiler.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Dave Jones <davej@redhat.com>
---
I do not see this a stable material - people running stable kernels
have less value of W=1.

And the amount of warnings are outright silly. We should really
divide this up a bit so W=1 is semi usefull.

	Sam

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d5f925a..b280284 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -73,7 +73,7 @@ KBUILD_EXTRA_WARNINGS += -Wnested-externs
 KBUILD_EXTRA_WARNINGS += -Wold-style-definition
 KBUILD_EXTRA_WARNINGS += $(call cc-option, -Woverlength-strings,)
 KBUILD_EXTRA_WARNINGS += -Wpacked
-KBUILD_EXTRA_WARNINGS += -Wpacked-bitfield-compat
+KBUILD_EXTRA_WARNINGS += $(call cc-option, -Wpacked-bitfield-compat)
 KBUILD_EXTRA_WARNINGS += -Wpadded
 KBUILD_EXTRA_WARNINGS += -Wpointer-arith
 KBUILD_EXTRA_WARNINGS += -Wredundant-decls