tests: add possibility to disable leak check for single test

In tests that are using external libraries (i. e. pthread) we
can get failure because of leaks in the external library.
Until we have some better solution (if ever), let these (and only these)
tests to disable leak checks.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>
display-test: disable leak check in tests that use pthread

pthread is leaking and it makes our tests fail.

Signed-off-by: Marek Chalupa <mchqwerty@gmail.com>