ecore_evas/wayland_shm: Fixed window resize.

ecore_evas/wayland_shm: Fixed window resize.

Using the server_allocation/allocation to determine the resize offset
was not completely precise, and causing the window to not always resize
correctly.

Additionally, calling evas_engine_info_set() on every resize step caused
the window content to blink and resize very slow, because the swap
buffer, swapper, and everything were being destroyed and recreated. Now
only the swapbuf_reconfigure is being called during the resize, which is
way faster.