Add TAP13 conformat output functions to kselftest.h.

Also add exit functions that output TAP13 exiting text, as well as
functions to keep track of testing progress.
Signed-off-by: NPaul Elder <paul.elder@pitt.edu>
Signed-off-by: NAlice Ferrazzi <alice.ferrazzi@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>