MFC boot loader path and RBX constant deduplication

r294765 (imp)

Move all the separate copies of the same strings into paths.h. There's
nothing machine specific about these.

r294765 (imp)

RBX_ defines are in rbx.h, move it there.

r294847 (imp)

Remove static from these two. They slipped through the cracks.

r294925 (imp)

Fix mistake when transitioning to the new defines with ZFS loader. I
hate adding yet another define, but it is the lessor of the evil
choices available. Kill another evil by removing PATH_BOOT3 and
replacing it with PATH_LOADER or PATH_LOADER_ZFS as appropriate.

Approved by: re (gjb)

MFC r293461:

Remove hidden "Not ufs" printfs from boot code

Sponsored by: Multiplay

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Fix build on powerpc.

Reviewed by: nwhitehorn

Use 32-bit ufs_ino_t instead of ino_t to keep boot2 small and prevent
unnecessary 64-bit math on 32-bit machines.

Sponsored by: Google Summer of Code 2011

Make sure to synchronize icache for the newly loaded loader. Not an issue
on most systems, when the relevant icache lines are not full.

MFC after: 2 weeks

Merge binutils 2.17.50 to head. This brings a number of improvements to
x86 CPU support, better support for powerpc64, some new directives, and
many other things. Bump __FreeBSD_version, and add a note to UPDATING.

Thanks to the many people that have helped to test this.

Obtained from: projects/binutils-2.17

Modify our boot block to pick an output device, without which boot1 will fail
on G4 machines. On the assumption that most people using FreeBSD on Apple
hardware are not using serial consoles, set boot1's output to screen. This
should be revisited. While here, reduce verbosity of boot1.

Add a simple HFS boot block implementation for booting PowerPC macs. It creates
a small HFS filesystem with a CHRP boot script and an early-stage bootloader
derived from the sparc64 boot block.

Obtained from: sparc64