tconnect.c: Function to open TCP connection

link cfunc
October 3, 1995; Gregg M. Townsend
Requires: Unix, dynamic loading
See also: fpoll.c
This file is in the public domain.

tconnect(hostname, portnum) establishes a TCP connection to the given
host and port, returning an Icon file f.

Note that seek(f) must be called when switching between input and output
on this bidirectional file.  Additionally, the DEC Alpha requires a call
to flush(f), after the seek, when switching from input to output.