distro: Add psmisc. * distro/packages/linux.scm (psmisc): New variable.
distro: linux-libre-headers: Move to (distro packages linux). * distro/packages/base.scm (linux-libre-headers): Move to... * distro/packages/linux.scm (linux-libre-headers): ... here.
distro: Add Linux-PAM. * distro/packages/linux.scm: New file. * Makefile.am (MODULES): Add it.