libobs: Don't use was_down for hotkey detection
From MSDN: "The behavior of the least significant bit of the return value
is retained strictly for compatibility with 16-bit Windows applications
(which are non-preemptive) and should not be relied upon."
This caused problems with hotkeys firing if the user pressed a hotkey key
in another application, followed by the modifier keys at any other time.
OBS would then think the hotkey key was just pressed based on the was_down
behavior and incorrectly trigger a hotkey event.
Fixes 0000443.