test harness: improve catching of usage errors in script 'test-driver'

test harness: improve catching of usage errors in script 'test-driver'

Fixes automake bug#14840.

* lib/test-driver: Catch and report usage errors where the caller has
forgotten to specify one of the mandatory options (--test-name,
--log-file, --trs-file) or has not passed any non-option argument.
Also, be sure to work correctly even when no '--' special argument
is passed to separate option from non-options arguments.
* THANKS: Update.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>