don't be paranoid about status script permissions

bash et al. also don't check for this and we did not check for a
proper owner anyways...
source ~/.dwm-startup from dwm-mitch

This allows to autostart of some programs after the X session is
completely intialized (ssh-agent, session manager etc.).  Useful if
dwm-mitch is called from a login manager via the dwm-mitch.desktop
entry.