add copyright notices for myself and Diego

Originally committed as revision 7107 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

 #!/bin/sh
 #
-# ffmpeg configure script (c) 2000, 2001, 2002 Fabrice Bellard
+# FFmpeg configure script
+#
+# Copyright (c) 2000, 2001, 2002 Fabrice Bellard
+# Copyright (c) 2005-2006 Diego Biurrun
+# Copyright (c) 2005-2006 Mans Rullgard
 #
 
 # make sure we are running under a compatible shell