www/node6: Update 6.11.4 -> 6.11.5

[bhughes]

Summary

www/node6: Update 6.11.4 -> 6.11.5

Update to the latest upstream v6.x release to address a remote DoS
vulnerability.

https://nodejs.org/en/blog/vulnerability/oct-2017-dos/
https://nodejs.org/en/blog/release/v6.11.5/

Approved by: robak (mentor)
Security: CVE-2017-14919
MFH: 2017Q4

Test Plan

$ pwd
/usr/ports/www/node6
$ portlint -C
WARN: Makefile: possible direct use of command "python" found. use ${PYTHON_CMD} instead.
WARN: Makefile: possible use of absolute pathname "/etc/make.conf".
WARN: Makefile: "IGNORE" has to appear earlier.
WARN: Makefile: "ONLY_FOR_ARCHS" has to appear earlier.
0 fatal errors and 4 warnings found.

http://35.176.84.170/data/latest-per-pkg/node6/6.11.5/

[robak]

LGTM.