wayland: fix configure flags' type

pkgs/development/libraries/wayland/default.nix

···
     sha256 = "d6b4135cba0188abcb7275513c72dede751d6194f6edc5b82183a3ba8b821ab1";
   };
 
-  configureFlags = "--with-scanner --disable-documentation";
+  configureFlags = [ "--with-scanner" "--disable-documentation" ];
 
   nativeBuildInputs = [ pkgconfig ];