games/scummvm: Add new options, fix QA warnings

* Introduce a TTS option to avoid possible QA stage warnings with build
  environments that have already libspeechd.so because the configure
  script automatically adds it as an additional dependency in that case.

  Set the option as non-default because it's only used by a small set of
  engines and pulls in quite a few dependencies.

* The same as above also applies for enviroments that have GTK3
  installed.  Disable the support for GTK3 for now, as it only affects
  the dialogs in the options menu and it does not cause any major
  changes, but also requires a lot of additional dependencies.

* Add another option, XENGINES, that also enables experimental engines.

* Bump PORTREVISION to force a rebuild due changed dependencies.

PR:		255217
Reported by:	Gian-Simon Purkert <gspurki@gmail.com>