localmodconfig: Use Kbuild files too

commit c0ddc8c7 upstream.

In kbuild it is allowed to define objects in files named "Makefile"
and "Kbuild".
Currently localmodconfig reads objects only from "Makefile"s and misses
modules like nouveau.

Link: http://lkml.kernel.org/r/1437948415-16290-1-git-send-email-richard@nod.at



Reported-and-tested-by: Leonidas Spyropoulos <artafinde@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>