According to https://github.com/NuxiNL/cloudlibc:
CloudABI is no longer being maintained. It was an awesome experiment,
but it never got enough traction to be sustainable.

There is no reason to keep it in FreeBSD.

Approved by:	ed (private mail)
Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D31923