Instead of just having an "EGL" renderer, there is now a separate
winsys for each platform. Currently they just directly copy the vtable
for the EGL platform so it is still only possible to have one EGL
platform compiled into Cogl. However the intention is that the
winsys-specific code for each platform will be moved into override
functions in the corresponding platform winsys.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
