telnetd: ifdef out a buggy error handling code path

telnetd: ifdef out a buggy error handling code path

Here, not handling the error is would just eat one input 0xff char.
Correct handling would need even more corner case handling,
as-is buggy handling corrupts the buffer.
Since we just been told by kernel that pty is ready,
EAGAIN should not be happening here anyway.

function                                             old     new   delta
telnetd_main                                        1798    1785     -13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>