dwrite/layout: Fix invalid index access to cluster array.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=45543
Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/dwrite/layout.c

@@ -1853,6 +1853,9 @@ static void layout_add_line(struct dwrite_textlayout *layout, UINT32 first_clust
 
         metrics.trailingWhitespaceLength += cluster->length;
         trailingspacewidth += cluster->width;
+
+        if (index == 0)
+            break;
     }
 
     /* Line metrics length includes trailing whitespace length too */