Fix build issues on OEL5

Turns out this is real easy, the compile errors are just in the security hooks for link and setuid hardening, and those don't exist in this older kernel.

Now I suppose I could hook into do_symlink or mabye even one of the selinux functions such as selinux_inode_link, but I didn't write these protections in the first place, and their author apparently doesn't have any interest in supporting OEL5. If you _really_ want these features, upgrade your OS already :)