kbuild: Build minimum in scripts/ when changing configuration

From: Ricky Beam <jfbeam@bluetronic.net>, me

With the increasing amount of programs located in scripts/, several
of which is dependent on the kernel configuration, it makes sense to
avoid building these too often.
With this patch only fixdep is build, the minimal requirement for running
any *config target

Makefile

@@ -253,12 +253,15 @@ RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn --exclude CV
 
 # Helpers built in scripts/
 
-scripts/docproc scripts/fixdep scripts/split-include : scripts ;
+scripts/docproc scripts/split-include : scripts ;
 
-.PHONY: scripts
+.PHONY: scripts scripts/fixdep
 scripts:
 	$(Q)$(MAKE) $(build)=scripts
 
+scripts/fixdep:
+	$(Q)$(MAKE) $(build)=scripts $@
+
 
 # To make sure we do not include .config for any of the *config targets
 # catch them early, and hand them over to scripts/kconfig/Makefile
@@ -336,8 +339,8 @@ include .config
 
 # If .config is newer than include/linux/autoconf.h, someone tinkered
 # with it and forgot to run make oldconfig
-include/linux/autoconf.h: scripts/fixdep .config
-	$(Q)$(MAKE) $(build)=scripts/kconfig silentoldconfig
+include/linux/autoconf.h: .config
+	$(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
 
 endif