st/mesa: Deal with empty textures/buffers in semaphore wait/signal.

The actual texture might not have been created yet.

Gitlab: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3257
CC: mesa-stable
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6788>
diff --git a/src/mesa/state_tracker/st_cb_semaphoreobjects.c b/src/mesa/state_tracker/st_cb_semaphoreobjects.c
index 51288a8..6d97413 100644
--- a/src/mesa/state_tracker/st_cb_semaphoreobjects.c
+++ b/src/mesa/state_tracker/st_cb_semaphoreobjects.c
@@ -109,7 +109,8 @@
          continue;
 
       bufObj = st_buffer_object(bufObjs[i]);
-      pipe->flush_resource(pipe, bufObj->buffer);
+      if (bufObj->buffer)
+         pipe->flush_resource(pipe, bufObj->buffer);
    }
 
    for (unsigned i = 0; i < numTextureBarriers; i++) {
@@ -117,7 +118,8 @@
          continue;
 
       texObj = st_texture_object(texObjs[i]);
-      pipe->flush_resource(pipe, texObj->pt);
+      if (texObj->pt)
+         pipe->flush_resource(pipe, texObj->pt);
    }
 }
 
@@ -141,7 +143,8 @@
          continue;
 
       bufObj = st_buffer_object(bufObjs[i]);
-      pipe->flush_resource(pipe, bufObj->buffer);
+      if (bufObj->buffer)
+         pipe->flush_resource(pipe, bufObj->buffer);
    }
 
    for (unsigned i = 0; i < numTextureBarriers; i++) {
@@ -149,7 +152,8 @@
          continue;
 
       texObj = st_texture_object(texObjs[i]);
-      pipe->flush_resource(pipe, texObj->pt);
+      if (texObj->pt)
+         pipe->flush_resource(pipe, texObj->pt);
    }
 
    /* The driver is allowed to flush during fence_server_signal, be prepared */