MFC r228444:

MFC r228444:

 - Define true and false in sys/types.h for _KERNEL consumers, and
   typedef bool.  Due to macro expansion it seemed better to use a
   typedef for kernel consumers (specifically ofed won't compile
   without more changes if a define is used).
 - <stdbool.h> should also not re-define bool/true/false if they are
   defined by <sys/types.h>.  It would probably be a programming error
   to define _KERNEL for user-space code, but downstream consumers
   like Isilon have already been including <stdbool.h> in kernel
   sources, and this protects that usage.
 - sizeof(_Bool) is not necessarily the same as sizeof(int), so kernel
   modules should be rebuilt with this change.  Bump __FreeBSD_version.

No KBI change is expected based on review of the code.

git-svn-id: svn://svn.freebsd.org/base/stable/9@229285 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f