kbuild: enable 'make CPPFLAGS=...' to add additional options to CPP

The variable CPPFLAGS is a wellknown variable and the usage by
kbuild may result in unexpected behaviour.

This patch replace use of CPPFLAGS with KBUILD_CPPFLAGS all over the
tree and enabling one to use:
make CPPFLAGS=...
to specify additional CPP commandline options.

Patch was tested on following architectures:
alpha, arm, i386, x86_64, mips, sparc, sparc64, ia64, m68k, s390

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

1 files changed, 1 insertions, 1 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index f4779cd1542f..08fbe6cd309d 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -1099,7 +1099,7 @@ When kbuild executes, the following steps are followed (roughly):
         specified options when building the target vmlinux.lds.
 
         When building the *.lds target, kbuild uses the variables:
-        CPPFLAGS        : Set in top-level Makefile
+        KBUILD_CPPFLAGS : Set in top-level Makefile
         EXTRA_CPPFLAGS  : May be set in the kbuild makefile
         CPPFLAGS_$(@F)  : Target specific flags.
                           Note that the full filename is used in this