ktest: Save test output

The test output may contain useful information; save it along with the
already-saved buildlog, dmesg, and .config.

Link: http://lkml.kernel.org/r/1321616131-21352-1-git-send-email-rabin@rab.in



Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>