Print remote IPv4 address on a dual-stack v6 socket in IPv4 format

Print remote IPv4 address on a dual-stack v6 socket in IPv4 format

Previously, the code would print IPv4-mapped format ("::ffff:1.2.3.4"),
which is technically correct but adds no extra value, and is confusingly
different from the output if using a v4 socket.  Print "1.2.3.4" instead,
whatever socket type is used.

Affects client IP address in log file, status output (mroute_addr_print_ex),
and environment (setenv_sockaddr).

The fact that a dual-stack socket was used is still visible in the initial
peer connect message in the log:
  '... Peer Connection Initiated with [AF_INET6]::ffff:1.1.3.4:53779'

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1419875325-96015-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9363