protocol: clarify multiple wl_surface.attach
protocol: clarify multiple wl_surface.attach

Explicitly say what happens with the wl_buffer.release event, if you
attach several wl_buffers without a commit in between.

Reported-by: David Herrmann <fb53b2ddb8d141e0cb39d7c67c2f81b6bc2eb0f7@googlemail.com>
Signed-off-by: Pekka Paalanen <6c0263d81461c956d504307112a4ce25eaacc3d1@gmail.com>

abooij/wayland,tulcod/wayland,eyolfson/wayland,abooij/wayland,tulcod/wayland,bitfactor/wayland,mchalupa/wayland,bitfactor/wayland,eyolfson/wayland,sir-murray/wayland,eyolfson/wayland,tulcod/wayland,bitfactor/wayland,mchalupa/wayland,abooij/wayland,mchalupa/wayland,sir-murray/wayland,sir-murray/wayland