The change to let individual tests decide to reboot the machine on
success of the entire test also prevented errors from rebooting
when an error was detected.

The "no_reboot" variable was only cleared if the test had
reboot_on_success set. But the no_reboot variable also prevents the test
rebooting when an error was detected even when REBOOT_ON_ERROR was set.

Add a new "reboot_success" variable that is used to determine if the
test should reboot on success and not touch the no_reboot variable.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>