www/nginx: Update fancyindex to 0.4.2

This release contains an important fix which can cause Nginx
to crash when a directory contains zero-sized (empty) files.
This bug has been present in all previous releases,
and all users are strongly encouraged to update to version 0.4.2.

PR: 224237
Submitted by: wosch
Approved by: tz (mentor)
MFH: 2017Q4
Differential Revision: https://reviews.freebsd.org/D13486