add @options[:udp_port] to definiton for runit template

udp_port was missing in the define but was present in the template. Having no value here resulted in a memcached command line like:
```
/usr/bin/memcached -v -m 64 -U -p 11211 -u nobody -l 0.0.0.0 -c 1024
```
Instead of:
```
/usr/bin/memcached -v -m 64 -U 11211 -p 11211 -u nobody -l 0.0.0.0 -c 1024
```
So memcached was starting, but not listening on UDP (OR TCP).