selinux: Allow defconfig to be selected when defined

To enable selinux you must 'export HAVE_SELINUX=true' in
terminal before you brunch
Change-Id: I6695b81a85e734cb95a620ae9cc2750c40ff7505
Merge remote-tracking branches 'rqdev/cm-10.1' and 'rqkang/cm-10.1' into cm-10.1