st/nine: Fix crash when deleting non-implicit swapchain

The implicit swapchains are destroyed when the device instance is
destroyed. However for non-implicit swapchains, it is not the case,
and the application can have kept an reference on the swapchain
buffers to reuse them.

Fixes problems with battle.net launcher.

Cc: "10.4" <mesa-stable@lists.freedesktop.org>
Tested-by: Nick Sarnie <commendsarnex@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Axel Davy <axel.davy@ens.fr>

src/gallium/state_trackers/nine/swapchain9.c

@@ -467,7 +467,7 @@ NineSwapChain9_dtor( struct NineSwapChain9 *This )
 
     if (This->buffers) {
         for (i = 0; i < This->params.BackBufferCount; i++) {
-            NineUnknown_Destroy(NineUnknown(This->buffers[i]));
+            NineUnknown_Release(NineUnknown(This->buffers[i]));
             ID3DPresent_DestroyD3DWindowBuffer(This->present, This->present_handles[i]);
             if (This->present_buffers)
                 pipe_resource_reference(&(This->present_buffers[i]), NULL);