Instead of having #ifdefs to hook into the normal EGL winsys, the KMS
winsys now overrides any winsys functions that it wants. Where the
winsys wants to hook into a point within a function provided by the
EGL winsys there is a EGL-platform vtable which gets set on the EGL
renderer data during renderer_connect. The KMS-specific data on all of
the structures is now allocated separately by the KMS winsys and is
pointed to by a new 'platform' pointer in the EGL data.
Reviewed-by: Robert Bragg <robert@linux.intel.com>