ivi-shell: multi screen support to calcuration of a mask of weston_surface.

ivi-shell: multi screen support to calcuration of a mask of weston_surface.

A weston_surface is transformed to multi screen coordinate, global
coordinate by matrix:m now.

Additionally, a mask needs to be calucated, taking account into,
- multi screen coordination: a destination rectangle of layer in the
  coordination is easily calcurated by adding weston_output.{x,y} in
  simple. This is because there is no scaled and rotated transformation.
- intersect inside of a screen the layer is assigned to. This is because
  overlapped region of weston surface in another screen shall not be
  displayed according to ivi use case.

Signed-off-by: Nobuhiko Tanibata <nobuhiko_tanibata@xddp.denso.co.jp>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>