packages/linux-pam: disable when using musl

Fixes: http://autobuild.buildroot.net/results/e33/e337d69420ad00b2cc4017d639a31803926f2353/



linux-pam needs some surgery to build under musl, so for the time being
disable it until the issues are solved. Also disables dependent package
python-pam, and dependent suboptions under openvmtools, rsh-redone and
util-linux.

Signed-off-by: Brendan Heading <brendanheading@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>