kernel32: Add tests for SetHandleCount + make tests pass for winversions >WINNT

[Louis Lenders]

>It's pretty unlikely that count would be larger than 0xffffffff.
I agree, but i thought we should mimic Windows-behaviour, and the tests showed that such large values are at least allowed. If this value is too large could you suggest another one?

> Also I don't think we need a version check.

The check is there as the tests show that there is a difference between ver < win98 and ver > WINNT. I don't know if there a are applications that depend on this difference really. Anyway, i could return something like min(65536,count) for all versions, is that ok? (i'll strip out the tests then, as they won't be passing then anymore)