ptest-perl/run-ptest: set exit code

ptest-perl/run-ptest: set exit code

Set exit code on the run-ptest script: though the logparser
looks for PASS/FAIL state, it can be still useful when running
the tests manually - when there is a lot of output, it is
easier to see the summary at the end if the test has actually
passed or failed without scrolling back.

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>