xvba_video_glx.c: fix query_surface_status() to report the true state, also on errors.

Be more strict in checking inside query_surface_status() function. It allowed
for reporting that all is ok on error. The function was therefor not reliable.

src/xvba_video.c

@@ -143,45 +143,50 @@ query_surface_status(
     VASurfaceStatus    *surface_status
 )
 {
-    int status;
+    int status, ret = -1;
+
+    if (!surface_status)
+        abort(); /* coding error */
 
     if (surface_status)
         *surface_status = VASurfaceReady;
 
     if (!obj_surface)
-        return 0;
+        return ret;
 
     switch (obj_surface->va_surface_status) {
     case VASurfaceRendering: /* Rendering (XvBA level) */
         ASSERT(obj_surface->used_for_decoding);
         if (!obj_context)
-            return 0;
+            return -1;
         if (!obj_context->xvba_decoder)
-            return 0;
+            return -1;
         if (!obj_surface->xvba_surface)
-            return 0;
+            return -1;
         status = xvba_sync_surface(
             obj_context->xvba_decoder,
             obj_surface->xvba_surface,
             XVBA_GET_SURFACE_STATUS
         );
         if (status < 0)
-            return -1;
+            goto out;
         if (status == XVBA_COMPLETED)
             obj_surface->va_surface_status = VASurfaceReady;
+        ret = 0;
         break;
     case VASurfaceDisplaying:
         status = query_surface_status_glx(driver_data, obj_surface);
         if (status < 0)
-            return -1;
+            goto out;
         if (status == XVBA_COMPLETED)
             obj_surface->va_surface_status = VASurfaceReady;
+        ret = 0;
         break;
     }
-
+out:
     if (surface_status)
         *surface_status = obj_surface->va_surface_status;
-    return 0;
+    return ret;
 }
 
 // Synchronize surface