[PATCH] mfplat: Fix playback rate handling in system time source.

[Marvin]

Hi,

While running your changed tests, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?

Full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=108312

Your paranoid android.


=== w7u_adm (32 bit report) ===

mfplat:
086c:mfplat: unhandled exception c0000005 at 6ECF7D1C

=== w7u_el (32 bit report) ===

mfplat:
0860:mfplat: unhandled exception c0000005 at 6ECE7D1C