broken (see bug #996), but less broken than Be's.
Also the Linux implementation is not perfect, as test 4 reveals: it waits for a
child with a certain process group, even if there is no child around anymore (because
the last child changed its process group. However, it will still return (and report
the correct error code) once this child exits.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20009 a95241bf-73f2-0310-859d-f6bbb57e9c96