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)

MFppc64:

Kernel sources for 64-bit PowerPC, along with build-system changes to keep
32-bit kernels compiling (build system changes for 64-bit kernels are
coming later). Existing 32-bit PowerPC kernel configurations must be
updated after this change to specify their architecture.

/* -> /*- for license, minor formatting changes

- use symbol for user-context offset
- fix szsigcode size declaration

Approved by: benno

- Rename the _C_LABEL macro to CNAME.
- Rename the _ASM_LABEL macro to ASMNAME.
- Add the HIDENAME macro which is used in libc's syscall stuff.

Commit of stuff that's been sitting in my tree for a while.

Highlights include:
- New low-level trap code from NetBSD. The high level code still needs a lot
of work.
- Fixes for some pmap handling in thread switching.
- The kernel will now get to attempting to jump into init in user mode. There
are some pmap/trap issues which prevent it from actually getting there though.

Obtained from: NetBSD (parts)