[PATCH] kbuild: CF=<arguments> passes arguments to sparse

Allows to add to sparse arguments without mutilating makefiles - just
pass CF=<arguments> and they will be added to CHECKFLAGS.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -334,7 +334,7 @@ KALLSYMS	= scripts/kallsyms
 PERL		= perl
 CHECK		= sparse
 
-CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
+CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ $(CF)
 MODFLAGS	= -DMODULE
 CFLAGS_MODULE   = $(MODFLAGS)
 AFLAGS_MODULE   = $(MODFLAGS)