provide default values for test scripts

provide default values for test scripts

Our test scripts currently require that the first argument be the
library or binary to be tested.  This makes integrating them with
automake which doesn't have a mechanism for passing specific arguments
to individual tests.  Instead, provide a default built from paths in the
environment which can be provided to all test scripts by automake.

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>