ws: G_LOG_DOMAIN fixes for clang

It seems that clang expands nested macros differently than gcc
so we need to redefine G_LOG_DOMAIN earlier in some cases.

Closes #569
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
agent: Call pam_acct_mgmt() when creating user session

This allows PAM to deny access for the user, so we now
respect HBAC.

Fixes #493
Closes #566