gdksurface-win32.c: Disable AeroSnap for surface if not resizable

AeroSnap essentially resizes the surface by all means, so if a surface
is not resizable, just bail out of the operation, even though it is
triggered by a move operation.

This matches what is done in other Windows applications.
13 jobs for disable-aerosnap-if-not-resizable in 50 minutes and 5 seconds (queued for 5 seconds)