bootstrap availablelang/go112 patch is here:
http://mikael.urankar.free.fr/FreeBSD/go/go-s://reviews.freebsd-arm64-bootstrap.tar.gz.org/D20336
There is a bug with base ld.lld on -current https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237692
Based on the work of some people (myfreeweb, bsd-hacker and coypoop (netbsd))