[PATCH] windowscodecs/tests: Fix a memory leak (Valgrind).

[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=55582

Your paranoid android.


=== wvistau64_he (task log) ===

Task errors:
The previous 1 run(s) terminated abnormally