TOMOYO: Merge headers.

Gather structures and constants scattered around security/tomoyo/ directory.
This is for preparation for adding garbage collector since garbage collector
needs to know structures and constants which TOMOYO uses.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>