Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6:
  kbuild: Make DEBUG_SECTION_MISMATCH selectable, but not on by default
  genksyms: Regenerate lexer and parser
  genksyms: Track changes to enum constants
  genksyms: simplify usage of find_symbol()
  genksyms: Add helpers for building string lists
  genksyms: Simplify printing of symbol types
  genksyms: Simplify lexer
  genksyms: Do not paste the bison header file to lex.c
  modpost: fix trailing comma
  KBuild: silence "'scripts/unifdef' is up to date."
  kbuild: Add extra gcc checks
  kbuild: reenable section mismatch analysis
  unifdef: update to upstream version 2.5

Makefile

@@ -102,6 +102,10 @@ ifeq ("$(origin O)", "command line")
   KBUILD_OUTPUT := $(O)
 endif
 
+ifeq ("$(origin W)", "command line")
+  export KBUILD_ENABLE_EXTRA_GCC_CHECKS := 1
+endif
+
 # That's our default target when none is given on the command line
 PHONY := _all
 _all:
@@ -1018,7 +1022,7 @@ hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm)
 
 PHONY += __headers
 __headers: include/linux/version.h scripts_basic FORCE
-	$(Q)$(MAKE) $(build)=scripts scripts/unifdef
+	$(Q)$(MAKE) $(build)=scripts build_unifdef
 
 PHONY += headers_install_all
 headers_install_all:
@@ -1263,6 +1267,7 @@ help:
 	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'
 	@echo  '  make C=1   [targets] Check all c source with $$CHECK (sparse by default)'
 	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'
+	@echo  '  make W=1   [targets] Enable extra gcc checks'
 	@echo  ''
 	@echo  'Execute "make" or "make all" to build all targets marked with [*] '
 	@echo  'For further info see the ./README file'