lang/erlang-runtime26: new port derived from erlang-runtime25

OTP-26 is the annual major release from Ericsson's Erlang/OTP team.

- https://www.erlang.org/news/164
- https://erlang.org/download/otp_src_26.0.readme

Reviewed by:	dumbbell
Sponsored by:	VMware, Inc.
Sponsored by:	SkunkWerks, GmbH
Differential Revision: https://reviews.freebsd.org/D40126