options, x11+cocoa: add option --cursor-autohide-delay
Add option --cursor-autohide-delay to control the number of milliseconds
with no user interaction before the mouse cursor is hidden.
There are two negative values with useful special meanings:
* A value of -1 prevents the cursor from hiding (useful for users
with multiple displays).
* A value of -2 prevents the cursor from showing upon activity.
The default is 1 second to keep the behaviour consistent with the
past X11 backend implementation.
Remove the vo_mouse_autohide field as it was always true.