cups: fix build without PAM

cups: fix build without PAM

Add upstream patch removing MD5 code that builds when PAM is not
enabled.

Fixes:
http://autobuild.buildroot.net/results/48d/48d53bdeceafdbb51756d5c0b9936ce7c98b4ddc/
http://autobuild.buildroot.net/results/13c/13cb03a8d0ae215c418fe2520a27b2940efd4a39/
http://autobuild.buildroot.net/results/fd3/fd3c56b60bb0411b38dc7279880d1fab7228c20a/

Cc: Olivier Schonken <olivier.schonken@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Olivier Schonken <olivier.schonken@gmail.com>
Signed-off-by: Baruch Siach &lt;<a href="mailto:baruch@tkos.co.il" target="_blank" rel="noreferrer">baruch@tkos.co.il</a>&gt;<br>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>