speech synth improvements

• fix old kernel param delimiter
• prepare for next upstream live-build generating its own speech synth entries

edit: of course once the new version of live-build is established and becomes a new minimum version, the kali hacks for adding speech synth menus can just go; the intention here is to prepare kali to do the right thing both with current and future live-build now, such that we do not end up in a situation of forgetting resulting in duplicate speech synth entries.