[PATCH] signal: use kill_pgrp not kill_pg in the sunos compatibility code

I am slowly moving to a model where all process killing is struct pid based
instead of pid_t based.  The sunos compatibility code is one of the last users
of the old pid_t based kill_pg in the kernel.  By being complete I allow for
the future removal of kill_pg from the kernel, which will ensure I don't miss
something.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>