BUG/MINOR: tcp-act: Don't forget to set the original port for IPv4 set-dst rule

BUG/MINOR: tcp-act: Don't forget to set the original port for IPv4 set-dst rule

If an IPv4 is set via a TCP/HTTP set-dst rule, the original port must be
preserved or set to 0 if the previous family was neither AF_INET nor
AF_INET6. The first case is not an issue because the port remains the
same. But if the previous family was, for instance, AF_UNIX, the port is not
set to 0 and have an undefined value.

This patch must be backported as far as 1.7.