Allow Core_WaitInactive() when already inactive.

It's being called unconditionally now, it was changed in the other one, so
I guess it needs changing here.
Don't show a dialog on quit when EmuThread hangs.

It's not like it will prevent PPSSPP from quitting.
Merge pull request #2571 from unknownbrackets/windows-ui

Fix delay when quitting with game paused