ddebug: fix use-after-free of streamout targets

Fixes: b47727a83ad6 ("ddebug: implement pipelined hang detection mode")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
diff --git a/src/gallium/drivers/ddebug/dd_draw.c b/src/gallium/drivers/ddebug/dd_draw.c
index a250171..e908410 100644
--- a/src/gallium/drivers/ddebug/dd_draw.c
+++ b/src/gallium/drivers/ddebug/dd_draw.c
@@ -767,7 +767,7 @@
    }
 
    dst->num_so_targets = src->num_so_targets;
-   for (i = 0; i < ARRAY_SIZE(src->so_targets); i++)
+   for (i = 0; i < src->num_so_targets; i++)
       pipe_so_target_reference(&dst->so_targets[i], src->so_targets[i]);
    memcpy(dst->so_offsets, src->so_offsets, sizeof(src->so_offsets));