Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Add definitions for TSTATE_MM_* and TSTATE_{I,X}CC_*.
Implement TSTATE_SECURE in terms of PSTATE_SECURE.

Add definitions for bits in condition code register and the load store
unit control registers. Move tstate definitions to their own file.

Submitted by: tmm