[3/3] ntdll/tests: Add tests for RtlRegisterWait.

[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=17078

Your paranoid android.


=== w7u (32 bit threadpool) ===
threadpool.c:1364: Test failed: WaitForSingleObject returned 258
threadpool.c:1375: Test failed: WaitForSingleObject returned 0

=== w864 (64 bit threadpool) ===
threadpool.c:613: Test failed: expected userdata >> 16 != 0, got 0