SELinux: Update keepalived custom policy

Found additional denials with keepalived unable able to read /proc.
Updated the custom policy to allow keepalived to read /proc.

These additional changes are temporary and should be removed
when the denials are fixed in the upstream selinux-policy.

Partial-Bug: 1379079
Change-Id: I30d74f80386e908822fcc6ff5ac3d4ae90fc4e27
SELinux: Fix /mnt/state/var/log/keepalived context

The default context mnt_t is incorrect. It should be var_log_t.

Bug: 1381770
Change-Id: I86a79ea1075ea2a6a567a78d628ab8a47f53ddd4
Ensure neutron rootwrap.d symlink is not nested

Before this change, if /etc/neutron/rootwrap.d existed already and
was a dir or a link to a dir, an additional symlink, named rootwrap.d
was created within the rootwrap.d dir, eventually causing the
neutron-rootwrap command to fail and exit with non-zero.

Change-Id: I2f11d7e93ef1445afd1a58e4dd110f7369ec93ab