Adds ngx-devel-kit requirement for set-misc-module

Set misc module requires ngx_devel_kit to be compiled in also (see
http://wiki.nginx.org/HttpSetMiscModule#Installation)

To recreate this issue simply brew install nginx-full --with-set-misc-module. This will result in the following compile time fail

```
error: ngx_devel_kit is required to build ngx_set_misc: please put it before ngx_set_misc.
```

Not sure this is the cleanest way to do this but this fixes the issue locally for me