Created attachment 271349 [details, diff] Proposed patch for espeakup-0.71.ebuild espeakup has a versioned dependency on virtual/linux-sources that is not allowed for an old-style virtual. Furthermore, a runtime dependency on kernel sources doesn't make much sense (and repoman warns about it). I believe that the proper way to handle it would be via CONFIG_CHECK from linux-info.eclass. Suggested modification for espeakup-0.71.ebuild is attached. A similar change would have to be applied to the live ebuild.
I took your patch and modified it a bit. There are two options that we should check for, CONFIG_SPEAKUP and CONFIG_SPEAKUP_SYNTH_SOFT both must be enabled. Also, I added error messages with the ERROR_* options. Thanks for the report and the patch.