test: sort-of autodetect whether we need root privileges

test: sort-of autodetect whether we need root privileges

It's not really autodetection, we just declare the test suites that need root
privs. But this way we can generically check for it from the main() that we
re-use across tests.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>