www/{nginx,nginx-devel,freenginx}: 3rd-party modules management

Point the MODSECURITY3 option at the owasp-modsecurity account, which now
hosts ModSecurity-nginx; the SpiderLabs path only works through GitHub's
redirect. Pin all three ports to the same commit 9eb44fd; they carried
v1.0.3, fd28e6a and v1.0.3.

Also restore two mangled lines in the freenginx MODSECURITY3 branch, which
had lost their first character, leaving the port without --with-ld-opt and
without the pcre2 dependency when the option was on.

Sponsored by: Netzkommune GmbH