user32:clipboard winex11.drv (KDE) interference

[Esme Povirk (they/them)]

I think the only correct way to fix this is to have our test code
retry (for some attempt/time limit) when OpenClipboard or functions
using it fail.

We could have wine library code that calls OpenClipboard do this, but
I'm not sure if there are compatibility implications if Windows does
not.

For winex11.drv to not interfere, we'd need some kind of wine-specific
interface to user32. I'm not sure to what extent that's possible (we
probably have to open the clipboard if the data we want isn't
rendered), and it's probably not worth it for an error that doesn't
come up in normal usage.