clipboard: initialise clipboard memory after creation
clipboard: initialise clipboard memory after creation

In case we don't, weston segfault in clipboard_set_selection
on:
if (clipboard->source)
		clipboard_source_unref(clipboard->source);

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