x86: Add some missing dependencies on config.h to x86's Makefile.inc.

These dependencies came indirectly through kconfig.h which was included
automatically with a -include option which was either part of INCLUDES or
specified directly.

A similar change was checked in for ARM upstream.

BUG=None
TEST=Built for falco.
BRANCH=None

Change-Id: I640b8115f6526c546fe5d251ef2c04e0e78e6ac9
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/170122
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index 3790698..39af26a 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -343,7 +343,7 @@
 	@printf "    CC         $(subst $(obj)/,,$(@))\n"
 	$(CC) -MMD -x assembler-with-cpp -E -I$(src)/include -I$(src)/arch/x86/include -I$(obj) -include $(obj)/build.h -include $(obj)/config.h -I. -I$(src) $< -o $@
 
-$(objgenerated)/bootblock.inc: $(src)/arch/x86/init/$(subst ",,$(CONFIG_BOOTBLOCK_SOURCE)) $(objutil)/romcc/romcc $(OPTION_TABLE_H)
+$(objgenerated)/bootblock.inc: $(src)/arch/x86/init/$(subst ",,$(CONFIG_BOOTBLOCK_SOURCE)) $(objutil)/romcc/romcc $(OPTION_TABLE_H) $(obj)/config.h
 	@printf "    ROMCC      $(subst $(obj)/,,$(@))\n"
 	$(CC) $(INCLUDES) -MM -MT$(objgenerated)/bootblock.inc \
 		$< > $(objgenerated)/bootblock.inc.d