Win32: Make PPSSPP DPI aware to avoid flickering in fullscreen on some PC hardware setups.

Attempts to fix https://github.com/hrydgard/ppsspp/issues/5181.

Feedback from people affected like @gitaarik would be appreciated. This fixes it for me, but I don't know if it'll fix it for everyone experiencing it.

This method isn't recommended by MSDN as I've mentioned several times, but since the XML method doesn't do anything, what other choice do we have? :\