Path composition for the relay log file that is stored into the relay index
file was not correct for windows.
mysql-test language does not provide primitives for portable path composition.
Fixed with storing only the basename part of the external "fake" relay log into
the relay index file.
Safety of removal of the dirname part of the relaylog is provided by logics of
`setup_fake_relay_log' that places the fake file into @@datadir directory.
It's a regression issue.
The reason of the bug appeared to be an error introduced into 5.1 source code.
A piece of code in Create_file_log_event::do_apply_event() did not have test
coverage which made make test and pb unaware.
Fixed with inverting the old value of the return value from
Create_file_log_event::do_apply_event().
The rpl test suite is extended with `rpl_cross_version' the file to hold
regression cases similar to the current.