[test-multithread] Disable FreeType funcs

test/api/test-multithread.c

@@ -153,8 +153,12 @@ main (int argc, char **argv)
   fill_the_buffer (ref_buffer);
 
   test_body ();
-  hb_ft_font_set_funcs (font);
-  test_body ();
+
+  /* hb-font backed by FreeType functions can only be used from
+   * one thread at a time, because that's FT_Face's MT guarantee.
+   * So, disable this, even though it works "most of the time". */
+  //hb_ft_font_set_funcs (font);
+  //test_body ();
 
   hb_buffer_destroy (ref_buffer);