desktop-shell: set the current size in the first 'resizing' configure event
desktop-shell: set the current size in the first 'resizing' configure event

Weston has sent the first 'resizing' configure event with width=height=0.
But resizing to that size doesn't make sense.
Instead, we now send the current width and height of the surface at the beginning
of resizing.

Signed-off-by: Ryo Munakata <b0e96e5000c47678832fb87f79b32c3d1828548c@gmail.com>

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