This adds the nginx module `ngx_http_proxy_connect_module` which allows
to tunnel HTTPS through an nginx proxy[1].
As this module contained patches for several nginx version, some minor
adjustments were needed:
* Allowed each entry in `nginxModules` to provide patches.
* Added an optional `supports` attribute to ensure that each module can
determine if it supports the currently built nginx version (e.g. stable
1.14 ATM or mainline 1.15 ATM).
[1] https://github.com/chobits/ngx_http_proxy_connect_module
37867dba74