host util-linux: disable login and su since they depend on PAM

This fixes the following errors when building util-linux v2.22.2 for
the host in case the PAM headers are missing:

  configure: error: login selected, but required PAM header file not available
  configure: error: su selected, but required PAM header file not available

Signed-off-by: Christophe Vu-Brugier <cvubrugier@lacie.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>