prepare: do not set termios.OPOST (#5)

> OPOST  Enable implementation-defined output processing.

According to [1] this is likely only turning "\n" into "\r\n", which is
required when another thread is dumping output, where currently this
would result into the following with pdb++:

    waited
          waited
                waited
                      (Pdb++) --Return--
                                        > /…/t-threads.py(19)__t2__()->None
                                                                           -> __import__('pdb').pdb.set_trace()

1: https://viewsourcecode.org/snaptoken/kilo/02.enteringRawMode.html#turn-off-all-output-processing

Author: blueyed

pyrepl/unix_console.py

@@ -359,7 +359,6 @@ def prepare(self):
         raw.iflag |= termios.ICRNL
         raw.iflag &= ~(termios.BRKINT | termios.INPCK |
                        termios.ISTRIP | termios.IXON)
-        raw.oflag &= ~termios.OPOST
         raw.cflag &= ~(termios.CSIZE | termios.PARENB)
         raw.cflag |= (termios.CS8)
         raw.lflag &= ~(termios.ICANON | termios.ECHO |