webassembly: Include lib in sys.path.

Following other ports.

Signed-off-by: Damien George <damien@micropython.org>

ports/webassembly/main.c

@@ -105,6 +105,7 @@ void mp_js_init(int heap_size) {
         mp_vfs_mount(2, args, (mp_map_t *)&mp_const_empty_map);
         MP_STATE_VM(vfs_cur) = MP_STATE_VM(vfs_mount_table);
     }
+    mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_lib));
     #endif
 }