www/p5-CGI-Application-Plugin-TT: make
p5-CGI-Application-Plugin-DevHelp optional

Currently, p5-CGI-Application-Plugin-DevHelp is a hard dependency in
p5-CGI-Application-Plugin-TT. However, C::A::P::TT operates just fine
without it. The attached patch turns the dependency into an OPTION
that defaults to on.

Just for the sake of having a reference,
http://cpansearch.perl.org/src/CEESHEK/CGI-Application-Plugin-TT-1.05/
META.yml lists it as a "recommends" but not a "requires."

PR: 196472
Differential Revision: https://reviews.freebsd.org/D1451
Submitted by: adamw
Approved by: marino(mentor)