winmm/tests: Add a small Sleep() to prevent a notification test from failing.

[Huw Davies]

On 13 Sep 2016, at 11:14, Marvin <testbot at winehq.org> wrote:
> 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=25773
> 
> Your paranoid android.
> 
> 
> === w864 (32 bit mci) ===
> mci: unhandled exception c0000005 at 77479E80
> 
> === w1064 (32 bit mci) ===
> mci: unhandled exception c0000005 at 7698851A

These are unrelated.

Huw.