If selinux is enabled the authlogin_nsswitch_use_ldap Boolean must
be enabled. This setting allows LDAP communications to the confined
LDAP/server port. This change includes a conditional for enabling this
Boolean only when selinux is in use.
Change-Id: If985f2434d28fcd33198929bf61f2a3a82e601fe
Closes-Bug: #1695002
(cherry picked from commit 90704a6017)