[PATCH v3] dinput: Cap the buffer size to 20.

[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=63139

Your paranoid android.


=== debian10 (64 bit WoW report) ===

dinput:
mouse.c:152: Test failed: Failed: 00000001
mouse.c:158: Test failed: Failed: 80070005
mouse.c:161: Test failed: Failed: 00000001
mouse.c:164: Test failed: Failed: 80070005
mouse.c:178: Test failed: GetDeviceData() failed: 00000000 cnt:0