[PATCH] allow /proc/config.gz to be built as a module

The driver for /proc/config.gz consumes rather a lot of memory and it is in
fact possible to build it as a module.

In some ways this is a bit risky, because the .config which is used for
compiling kernel/configs.c isn't necessarily the same as the .config which was
used to build vmlinux.

But OTOH the potential memory savings are decent, and it'd be fairly dumb to
build your configs.o with a different .config.
Signed-off-by: NAndrew Morton <akpm@google.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

init/Kconfig

@@ -202,7 +202,7 @@ config AUDITSYSCALL
 	  ensure that INOTIFY is configured.
 
 config IKCONFIG
-	bool "Kernel .config support"
+	tristate "Kernel .config support"
 	---help---
 	  This option enables the complete Linux kernel ".config" file
 	  contents to be saved in the kernel. It provides documentation

scripts/Makefile

@@ -13,7 +13,7 @@ hostprogs-$(CONFIG_VT)           += conmakehash
 hostprogs-$(CONFIG_PROM_CONSOLE) += conmakehash
 hostprogs-$(CONFIG_IKCONFIG)     += bin2c
 
-always		:= $(hostprogs-y)
+always		:= $(hostprogs-y) $(hostprogs-m)
 
 # The following hostprogs-y programs are only build on demand
 hostprogs-y += unifdef