i965: Support stereoscopic configs

The i965 driver now adds a duplicate stereoscopic config to all of its
configs. If one of these configs is used then it will create a renderbuffer
for the front and back right buffer attachments.
specs: Add a way to query multiple views from a wayland buffer

the EGL_WL_bind_wayland_display_spec now has an extra attribute to
eglCreateImageKHR to select a particular view of a wayland buffer. This can be
used to get a texture of one of the eyes of a stereoscopic buffer. The buffer
number of views can be queried by passing EGL_MULTIVIEW_VIEW_COUNT_EXT to
eglQueryWaylandBufferWL.
Add stereoscopic support to platform_wayland
stereo create image wayland
Add the EGL_MESA_sub_image extension

This extension is used to create an EGLImage from a subregion of another
EGLImage. There's no use case for this apart from to test the createSubImage
method of the DRIimage interface.