st/nine: Ignore window size if error

Check GetWindowInfo and ignore the computed sizes
if there is an error.

Fixes a regression caused by earlier commit when
using old wine gallium nine patches.

Should also address a crash at window destruction.

Related issues:
 https://github.com/iXit/Mesa-3D/issues/331
 https://github.com/iXit/Mesa-3D/issues/332



Cc: mesa-stable@lists.freedesktop.org
Fixes: 2318ca68 ("st/nine: Handle window resize when a presentation buffer is used")
Signed-off-by: Axel Davy <davyaxel0@gmail.com>
(cherry picked from commit 86666f05)
[Emil: resolve trivial conflicts]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

Conflicts:
	src/gallium/state_trackers/nine/swapchain9.c