Testlib.selftest: Improve process execution, run on openSUSE.

Give processes a more complete environment (openSUSE
requires more variables to start an X11-process),
add test column indicating whether a test is
supposed to crash. If it is not, report crash reason.

Change-Id: I1e0ad59824963f69ee425f331d845741be2b3928
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
Doc: Q_REVISION/Q_INVOKABLE are added to declaration not definition.

Change-Id: Ia06d33df1b5d38783e22b0c45956a5154338ed33
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>