add linux wayland platform

this make cobalt run with wayland on Ubuntu 17.10
or any other Ubuntus build local wayland and Weston.

need mesa 10.1.3
configuration:
./autogen.sh --prefix=$WLD --enable-egl --enable-opengl  --enable-gles2
--with-egl-platforms=x11,wayland,drm --enable-gbm --enable-shared-glapi
--with-gallium-drivers=r600,swrast,nouveau --enable-gallium-egl
--disable-gallium-llvm
building refer:
https://wayland.freedesktop.org/building.html

dependences:
https://cobalt-review.googlesource.com/c/cobalt/+/4450
https://cobalt-review.googlesource.com/c/cobalt/+/4430

Change-Id: Ia1caf124fb8ba5e0555dc62a955338bcf8e73cd5