weston-launch: Provide a default version that doesn't require PAM
weston-launch requires PAM for starting weston as a non-root user.
Since starting weston as root is a valid use case by itself, if PAM is not available, provide a default version of weston-launch without non-root-user support.
Signed-off-by: Tom Hochstein tom.hochstein@nxp.com Signed-off-by: Jussi Kukkonen jussi.kukkonen@intel.com Signed-off-by: Randy 'ayaka' Li ayaka@soulik.info