Commonly used desktop environments such as xfce4 and gnome
on debian sid can flood the graphics drivers with cursor
updates.  Because the current implementation is waiting
for a vblank between cursor updates, this will cause the
display to hang for a long time since a typical refresh
rate is only 60Hz.

This is unnecessary and unexpected by user mode software,
so simply swap out the cursor frame buffer without waiting.
Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/20170224015431.24583-1-mzoran@crowfest.net