Signed-off-by: NMans Rullgard <mans@mansr.com>

This is based on the original work by Baptiste Coudurier.

Regression test reference updates are due to the extra output
from tiny_psnr.

Patch by Vitor Sessak

Originally committed as revision 24132 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 22155 to svn://svn.ffmpeg.org/ffmpeg/trunk

With this change, the output is checked immediately after each test
has run.  This means commands like "make regtest-mpeg2" can now be
used to run a single test and get meaningful results.

By default, make will abort if any test fails.  To run all tests
regardless, use make -k.

Originally committed as revision 21254 to svn://svn.ffmpeg.org/ffmpeg/trunk