ktest: Have wait on stdio honor bug timeout

After a bug is found, the STOP_AFTER_FAILURE timeout is used to
determine how much output should be printed before breaking out
of the monitor loop. This is to get things like call traces and
enough infromation about the bug to help determine what caused it.

The STOP_AFTER_FAILURE is usually much shorter than the TIMEOUT
that is used to determine when to quit after no more stdio is given.

But since the stdio read uses a wait on I/O, the STOP_AFTER_FAILURE is
only checked after we get something from I/O. But if the I/O does
not return any more data, we wait the TIMEOUT period instead, even
though we already triggered a bug report.

The wait on I/O should honor the STOP_AFTER_FAILURE time if a bug has
been found.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>