MFH: r416371

Update to upstream version 4.11.0

Extensive changelog on http://code.call-cc.org/releases/4.11.0/NEWS-4.11.0
including security fixes for Specialisation rules for string-{ref,set!}, bit-set?
and move-memory no longer use unchecked C functions which could
result in undefined behaviour, including buffer overruns.

While on it: Pet portlint

PR: 209810
Submitted by: vmagerya@gmail.com (maintainer)
Reported by: philneaton95@gmail.com

Approved by: ports-secteam (junovitch)