[PATCH] kbuild: build a single module using 'make dir/module.ko'

Using the syntax:
make dir/module.ko

kbuild now allows one to build a module including the final link stage.
This is usefull when one only wants to compile a single module and thus do
not have to wait until a full kernel has finished compiling.  Tested by:
randy_dunlap <rdunlap@xenotime.net>

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>