Realip: port support in X-Real-IP and X-Forwarded-For.

Realip: port support in X-Real-IP and X-Forwarded-For.

Now, the module extracts optional port which may accompany an
IP address.  This custom extension is introduced, among other
things, in order to facilitate logging of original client ports.
Addresses with ports are expected to be in the RFC 3986 format,
that is, with IPv6 addresses in square brackets.  E.g.,
"X-Real-IP: [2001:0db8::1]:12345" sets client port ($remote_port)
to 12345.