arm soft div and mod performance plays an important part
in runtime performance.

The currently implementation is very stable, but we believe
we can best it. This benchmark provides a reference point.

linux/arm omap4 pandaboard

BenchmarkUint32Div7     10000000               298 ns/op
BenchmarkUint32Div37    10000000               298 ns/op
BenchmarkUint32Div123   10000000               298 ns/op
BenchmarkUint32Div763   10000000               298 ns/op
BenchmarkUint32Div1247  10000000               299 ns/op
BenchmarkUint32Div9305  10000000               298 ns/op
BenchmarkUint32Div13307 10000000               298 ns/op
BenchmarkUint32Div52513 10000000               298 ns/op
BenchmarkUint32Div60978747      10000000               298 ns/op
BenchmarkUint32Div106956295     10000000               297 ns/op
BenchmarkUint32Mod7     10000000               280 ns/op
BenchmarkUint32Mod37    10000000               280 ns/op
BenchmarkUint32Mod123   10000000               280 ns/op
BenchmarkUint32Mod763   10000000               280 ns/op
BenchmarkUint32Mod1247  10000000               280 ns/op
BenchmarkUint32Mod9305  10000000               280 ns/op
BenchmarkUint32Mod13307 10000000               280 ns/op
BenchmarkUint32Mod52513 10000000               280 ns/op
BenchmarkUint32Mod60978747      10000000               280 ns/op
BenchmarkUint32Mod106956295     10000000               280 ns/op

R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6258067