Add XFAIL autotest for QBS-537.

Change-Id: I98aa65cee4e448efa6b9ab32f2165e4cc77429ec
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Introduce abstraction layer for QSKIP.

We might want to skip tests in other files as well.

Change-Id: Ia2352fdf472b461fb3d9ed6134789b4f56d126e8
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>