Provide PowerPC optimised implementations of callish prim ops.
The generic implementation of quotient remainder prim ops uses
a division and a remainder operation. There is no remainder on
PowerPC and so we need to implement remainder "by hand" which
results in a duplication of the divide operation when using the
Avoid this duplication by implementing the prim op in the native
Use PowerPC's instructions for long multiplication.
Addition and subtraction
Use PowerPC add/subtract with carry/overflow instructions
MO_Clz and MO_Ctz
Use PowerPC's CNTLZ instruction and implement count trailing
zeros using count leading zeros
Implement an algorithm given by Henry Warren in "Hacker's Delight"
using PowerPC divide instruction. TODO: Use long division instructions
when available (POWER7 and later).