zink: force threadsafe mapping for query results when necessary

this would otherwise use the ctx-based slab allocator, which races
and crashes

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12015>

src/gallium/drivers/zink/zink_query.c

@@ -432,6 +432,9 @@ get_query_result(struct pipe_context *pctx,
 
    if (!wait)
       flags |= PIPE_MAP_DONTBLOCK;
+   if (query->base.flushed)
+      /* this is not a context-safe operation; ensure map doesn't use slab alloc */
+      flags |= PIPE_MAP_THREAD_SAFE | PIPE_MAP_UNSYNCHRONIZED;
 
    util_query_clear_result(result, query->type);