This test will treat all non-zero return codes as failures, it will
make the pmtu.sh test script being marked as FAILED when some
sub-test got skipped.
Improve the result processing by
* Only mark the whole test script as SKIP when all of the
sub-tests were skipped
* If the sub-tests were either passed or skipped, the overall
result will be PASS
* If any of them has failed with return code 1 or anything bad
happened (e.g. return code 127 for command not found), the
overall result will be FAIL
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>