net/libwebsockets: update to 2.1.1

[ultima]

Summary

• Updated to 2.1.1

Changelog: https://github.com/warmcat/libwebsockets/blob/v2.1-stable/changelog#L4

PR\: 220080
Sumitted by\: Iblis Lin <[e-mail]> (maintainer)
Reviewed by\: lifanov (mentor), matthew (mentor)
Approved by\: lifanov (mentor), matthew (mentor)
Differential Revision\: https://reviews.freebsd.org/DXXXXX

Test Plan

portlint:
WARN: Makefile: for new port, make $FreeBSD$ tag in comment section empty, to make SVN happy.
0 fatal errors and 1 warning found.

poudriere:
103i386
103amd64
110i386
110amd64
12i386
12amd64

[matthew]