Changeset 94e3c83 in rtems

bsp/tms570: ensure that change of SCI baudrate is not applied in the middle of character Tx.

The rtems_monitor_task() setups/updates termios attributes
of the opened TTY and if there is ongoing some other output
it leads to the stuck.

It would be better to use some termios API function which
would call drainOutput() in rtems/cpukit/libcsupport/src/termios.c.
But functionality is not accessible outside of core termios
implementation.

The loop waiting for last character to be sent has to be there anyway
because hardware does not provide Tx machine/shift register empty
interrupt.

Closes #2794