When built with "no-speechd", TTS settings are still shown under Configure->Settings->Notifications. This can be very confusing when one is trying to get TTS to work by tweaking settings there. (I didn't notice the 'speech' USE flag for a couple days.)
The ideal solution would be to have TTS settings visible, but grayed out. This would indicate that TTS is possible, but disabled or unavailable somehow. That would be far better than tweaking the settings and still hearing absolutely nothing...
Discovered on my Gentoo system. Bug on bugs.gentoo.org here: https://bugs.gentoo.org/show_bug.cgi?id=457552
Attached is a screenshot of the dialog still displaying the offending settings.