Make the compilation of PIDL produce the same results if the content hasn't changed

Pick up change from Samba:

    commit 4986359816704f38d4fad3ddd0d07a0f0a25b335
    Author: Matthieu Patou <mat@matws.net>
    Date:   Mon Sep 22 21:52:14 2014 -0700

    pidl: Make the compilation of PIDL producing the same results if the content hasn't change

    Newer perl versions don't generate stable results anymore.

    Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Change-Id: Ifced47229b3033d1fae494adff0dee6671304812
Reviewed-on: https://code.wireshark.org/review/5090
Reviewed-by: Guy Harris <guy@alum.mit.edu>