Add more page numbers from PowerPC version 2.01. Remove "xnop" not in
2.01, add "mtcr" from 2.01. Add "lwarx" and the other instructions
from Book II. I did not try all the newly added instructions, but
these seem to work: dcbt, dcbtst, icibi, isync, lwarx, stwcx., mftb,
mftbu
In man/powerpc_as.6 (not installed), add a summary of the registers
and addressing modes (like in i386_as.6), describe short forms, update
description of hi16/ha16, add CAVEATS about instructions that some
processors can't run.
