Submodules: Use "ignore" settings from .gitmodules too for diff and status

Submodules: Use "ignore" settings from .gitmodules too for diff and status

The .gitmodules file is parsed for "submodule.<name>.ignore" entries
before looking for them in .git/config. Thus settings found in .git/config
will override those from .gitmodules, thereby allowing the local developer
to ignore settings given by the remote side while also letting upstream
set defaults for those users who don't have special needs.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>