[PATCH] Add CONFIG_HEADERS_CHECK option to automatically run 'make headers_check'

In order to encourage people to notice when they break the exported
headers, add a config option which automatically runs the sanity checks
when building vmlinux.  That way, those who use allyesconfig will notice
failures.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Makefile b/Makefile
index 274b780..f242829 100644
--- a/Makefile
+++ b/Makefile
@@ -741,6 +741,9 @@
 
 # vmlinux image - including updated kernel symbols
 vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) FORCE
+ifdef CONFIG_HEADERS_CHECK
+	$(Q)$(MAKE) headers_check
+endif
 	$(call if_changed_rule,vmlinux__)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
 	$(Q)rm -f .old_version