src/xdg.c: sync move with pending resize

src/xdg.c: sync move with pending resize

Before this patch, configuring a surface with a new size,
immediately followed up by one or more view_move() calls
would move the surface to the new coordinates immediately
without waiting for the resize. This caused visual glitches
when for example dragging a maximized window: the position
would change but the size was still that of a maximized
window.

This patch fixes that by just ignoring view_move() requests
(but still updating view->pending) if there is a configure
request pending. Once the client commit comes in the new
size will be applied as usual.