number if strerror_r() did not succeed for whatever reason.
This avoids the need for the application to fill the string in case
strerror_r() fails, for example because the error code is not known.
Originally committed as revision 23015 to svn://svn.ffmpeg.org/ffmpeg/trunk
instead which is semantically equivalent.
See the thread:
Subject: [FFmpeg-devel] [RFC] The meaning of AVERROR_NOTSUPP
Date: Sat, 27 Mar 2010 00:51:13 +0100
Originally committed as revision 22981 to svn://svn.ffmpeg.org/ffmpeg/trunk