Make variable containing port number an ushort in the sockets sample.

Make variable containing port number an ushort in the sockets sample.

A port number is an unsigned short, not long, so don't make it long just
because wxCmdLineParser doesn't provide a convenient way to get the value of
an unsigned short option (it would be nice if it did...).

This fixes the problem with using "%d" format specifier with a long variable
as this resulted in an assert under LP64 systems.

See #14311.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71443 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775