MFH: r526604

www/p5-Gantry: correctly escape $

In make(1), "$$" is the escaped version of "$", rather than the expected
"\$". this expression was getting passed through to ${REINPLACE_CMD} as
"s,\NV{..." rathern than the expected "s,$ENV{..." -- bug #229925 makes \N
an illegal expression, as ordinary characters will be disallowed from being
escaped in preparation for future changes to grant some of these escape
sequences GNU-extended behavior.

PR: 240310
Approved by: koobs (mentor), bapt (mentor)
Approved by: portmgr (maintainer timeout: 4 months, blanket: bugfix)
Differential Revision: https://reviews.freebsd.org/D23701

Approved by: ports-secteam (blanket: bugfix)