ktest: Added force stop after success and failure

Added the options STOP_AFTER_SUCCESS and STOP_AFTER_FAILURE to
allow the user to give a time (in seconds) to stop the monitor
after a stack trace or login has been detected. Sometimes the
kernel constantly prints out to the console and this may cause
the test to run indefinitely.

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