For some reason, this never existed before. Add VOCTRL_GET_DISPLAY_RES
and use it to obtain the current display's resolution from each
vo/windowing backend if applicable. Users can then access the current
display resolution as display-width and display-height as per the client
api. Note that macOS/cocoa was not attempted in this commit since the
author has no clue how to write swift.
Dudemanguy
a88fdfde0c