[PATCH] mstask: Fix some memory leaks on error path (Valgrind).

[Marvin]

Hi,

While running your changed tests on Windows, 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=47201

Your paranoid android.


=== debian9 (32 bit Chinese:China report) ===

mstask:
task_scheduler.c:498: Test failed: got 0x80070020

=== debian9 (32 bit WoW report) ===

mstask:
task_scheduler.c:498: Test failed: got 0x80070020