Remove now unused step variable.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

Right now those muxers use the default timebase in all cases(1/90000).

This patch avoid unnecessary rescaling and makes the printed timestamps
more readable.

Also, extend the printed information to include the timebases and packet
pts/duration and align the columns.

Obviously changes the results of all fate tests which use those two
muxers.

This adds a "fate" make target which runs the full FATE test suite.
Individual tests can be run with "make fate-$testname".

The location of the FATE test samples must be specified with the
--samples=PATH option to configure.

The tests/fate-update.sh script regenerates the references files and
test list from the online FATE database.  These are checked in since
generating them requires non-standard tools.

Originally committed as revision 22552 to svn://svn.ffmpeg.org/ffmpeg/trunk