Enable SECURITY_NETWORK_XFRM

[Eric Paris]

Right before FC6 we turned off CONFIG_SECURITY_NETWORK_XFRM since there
was a lot of development still going on in that areas especially
concerning secid reconciliation between that and secmark.  The
reconciliation work was killed upstream and XFRM labeling has been
worked on upstream and has been tested by the LSPP group for quite some
time now with success.

I'd like to get both of them turned back on so Fedora users can make use
of xfrm labeled networking.

-Eric