Check for symlinks in home directory path as logging-in user
    
    AllowChrootSymlinks off could cause login failures depending on filesystem
    permissions: use the IDs of the logging-in user to perform the directory
    walk, looking for symlinks, to be more consistent with similar checks done
    during login (#1443507, upstream bug 4306)
    
    Also, require perl(Crypt::CrackLib) unconditionally now (for ftpasswd)