mvcase REQUIRE shhopt. That's is right. mvcase REQUIRE shhopt.h. Yeah. shhopt don't install shhopt.h in /usr/include. That's bad. :)
I forgot... For anyone that need to use mvcase before the corrected ebuild: just add insinto /usr/include doins shhopt.h in the shhopt-1.1.7.ebuild
Maintainer has been MIA for ages, re-assign wrt Bug 24623
Thanks, fixed in CVS.