This allows building shared libraries on AMD64 again.
based on a patch by Diego 'Flameeyes' Pettenò and suggestions by Michael
original thread:
Date: Wed, 18 Apr 2007 11:26:12 +0200
Subject: [Ffmpeg-devel] [PATCH] (try 2) Build shared libraries on AMD64 again

Originally committed as revision 8849 to svn://svn.ffmpeg.org/ffmpeg/trunk