Fix Cairo vs. wl_shm pixel formats on big-endian
Background: wayland#11 (closed)
Weston clients, that use Cairo for drawing, use the Cairo ARGB format. They translate map this format unconditionally to WL_SHM_FORMAT_ARGB8888
which is correct on little-endian machines.
That is wrong on big-endian machines. On big-endian machines, the Cairo ARGB format corresponds to WL_SHM_FORMAT_BGRA8888
instead.
If Weston running on big-endian machine does not support WL_SHM_FORMAT_BGRA8888
, then that support will need to be added.