- Termios: cf{get,set}{i,o}speed can handle arbitrary speed values.
- The value is stored in the appropriate fields of the termios structure
in this case. The old constants (stored in the flags) are preserved
for BeOS binary compatibility.
- Adjust the FTDI FT232* driver to accept custom rates, by replacing the
hardcoded regster values with a function that will compute it
according to FTDI documentation (confirmed giving the same values for
the existing baudrates).