Faith Ekstrand authored Jan 13, 2015 and Keith Packard committed Jan 23, 2015

The original drmmode_glamor_new_screen_pixmap function was specific to the
primary screen pixmap.  This commit pulls the guts out into a new, more
general, drmmode_set_pixmap_bo function for setting a buffer on a pixmap.
The new function also properly tears down the glamor bits if the buffer
being set is NULL.  The drmmode_glamor_new_screen_pixmap function is now
just a 3-line wrapper around drmmode_set_pixmap_bo.

v2 Jason Ekstrand <jason.ekstrand@intel.com>:
 - Re-arranged code in drmmode_set_pixmap_bo and
   drmmode_glamor_handle_new_screen_pixmap so that glamor_set_screen_pixmap
   only gets called for the screen pixmap
 - Guard the call to glamor_set_screen_pixmapa with a drmmode->glamor check

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>