[apparmor] PATCH [1/2] have caching respect include time stamps

[John Johansen]

This patch changes how cache validation is done, by moving it post
parsing, and precompilation of policy.  This allows finding the most
recent text time stamp during parsing and this is then compared to
the cache file time stamp.

While this is slightly slower than the cache file check that only
validated against the profile file it fixes the bug where abstraction
updates do not cause the cache file to become invalid.

Nominated for 2.5.1