Revision 1670017

Add new %{xxx}p with xxx==local or xxx===remote
to allow logging remote and/or local port in the
access log.

Same xxx values as in Apache httpd, except httpd
also allows "canonical".

Logging remote ports can be very useful when trying
to filter network dumps for problems, that one can
detect in the access log but only analyze on the
network layer.

Backport of r1669882 from trunk resp.
r1669896 from tc8.