pkg/57340: Add the predefined option gssapi to www/nginx

[lloyd%must-have-coffee.gen.nz@localhost]

>Number:         57340
>Category:       pkg
>Synopsis:       Add the predefined option gssapi to www/nginx
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 10 00:05:00 +0000 2023
>Originator:     Lloyd Parkes
>Release:        9.3
>Organization:
Must Have Coffee
>Environment:
NetBSD wax.must-have-coffee.gen.nz 9.3_STABLE NetBSD 9.3_STABLE (GENERIC) #0: Mon Oct  3 11:15:41 NZDT 2022  lloyd%riftsweeper.must-have-coffee.gen.nz@localhost:/home/lloyd/NetBSD/objdir/sys/arch/amd64/compile/GENERIC amd64
>Description:
www/nginx doesn't support the predefined pkgsrc option "gssapi" even though a suitable module exists on Github. This patch adds the spnego-http-auth module by stnoonan to Nginx when it is built with the gssapi option. 

>How-To-Repeat:
Add gssapi to your default options in /etc/mk.conf and then run "make" in www/nginx.

>Fix:
Apply the diff from https://gist.github.com/lparkes/4d5fa1e63dee17d2d91cb4865d6e1011