www/nginx-devel: update third-party http_substitutions_filter module

Update the third-party module to its recent version to support
both PCRE1 and PCRE2 libraries.

Bump PORTREVISION.

Idea from: http://hg.nginx.org/pkg-oss/rev/45cb552c6860
Thanks to: Mikhail Isachenkov <mikhail.isachenkov@nginx.com>