window.c: Don't allocate proxy manually
window.c: Don't allocate proxy manually

With the wayland change to automatically allocate the client side proxy
manually, we can now drop the code (and the FIXME) that did that and just
receive the proxy from the callback arguments.

giucam/weston,mchalupa/weston,jonnylamb/weston,sir-murray/weston,eyolfson/weston,Fantu/compositor-spice,jonnylamb/weston,kwm81/weston,kwm81/weston,xorgy/weston,sir-murray/weston,eyolfson/weston,Gnurou/weston,udoprog/weston,mchalupa/weston,krezovic/weston,xorgy/weston,krezovic/weston,Tarnyko/weston-xdg_surface_present,udoprog/weston,Tarnyko/weston-xdg_surface_present,Gnurou/weston,giucam/weston,Fantu/compositor-spice,Fantu/compositor-spice