Request a version bump of libsigsegv to 2.4, as its needed for asymptote (bug #82871) and apparently v2.2 in portage is buggy (bug #82871, comment #60). I bumped the ebuild locally and it worked but I had to remove the macos patch.
turns out, a new asymptote (1.11) will work with the older libsigsegv 2.4 so I'm removing the block on bug #82871
In tree now, fixed.