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)

Fix some ifdef logic in the libc syncicache() bit that I somehow missed in the
last commit. Now it really can use a runtime-set cacheline size.

Allow the cacheline size on PowerPC to be set at runtime. This is essential for
supporting 64-bit CPUs, which often have 128-byte cache lines instead of the
standard 32.

Fix bogon in previous commit: <machine/cpu.h> is still needed.

The definition of CACHELINESIZE moved from <machine/cpu.h> to
<machine/md_var.h>.

Include <stdlib.h> to get abort() prototype.

Minimal libc for PowerPC.

Reviewed by: benno

Approved by: re (blanket)