kbuild: Use -isystem `gcc --print-file-name=include`

Using "-nostdinc -isystem `gcc --print-file-name=include" let
us see full path to compiler specific files when compiling with make V=1
Furthermore it lets us use same definition for sparse (CHECKFLAGS) and the kernel.
Tested with gcc 3.3.4 only.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -330,7 +330,10 @@ DEPMOD		= /sbin/depmod
 KALLSYMS	= scripts/kallsyms
 PERL		= perl
 CHECK		= sparse
+
+NOSTDINC_FLAGS := -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__
+CHECKFLAGS     += $(NOSTDINC_FLAGS)
 MODFLAGS	= -DMODULE
 CFLAGS_MODULE   = $(MODFLAGS)
 AFLAGS_MODULE   = $(MODFLAGS)
@@ -338,7 +341,6 @@ LDFLAGS_MODULE  = -r
 CFLAGS_KERNEL	=
 AFLAGS_KERNEL	=
 
-NOSTDINC_FLAGS  = -nostdinc -iwithprefix include
 
 # Use LINUXINCLUDE when you must reference the include/ directory.
 # Needed to be compatible with the O= option

scripts/Makefile.build

@@ -83,7 +83,6 @@ __build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
 
 # Linus' kernel sanity checking tool
 ifneq ($(KBUILD_CHECKSRC),0)
-  CHECKFLAGS += -I$(shell $(CC) -print-file-name=include)
   ifeq ($(KBUILD_CHECKSRC),2)
     quiet_cmd_force_checksrc = CHECK   $<
           cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;