[FR] human readable name of benchmark

[karthikeyann]

https://github.com/google/benchmark#running-a-subset-of-benchmarks As shown in the readme.md, https://github.com/google/benchmark/blame/master/README.md#L424

The benchmark name contains the state.range values as human readable format. (eg. 32k) But the current code does not provide any switches or automatic way to format these numbers to human readable format.

Benchmark              Time           CPU Iterations
----------------------------------------------------
BM_memcpy/32          11 ns         11 ns   79545455
BM_memcpy/32k       2181 ns       2185 ns     324074

Describe the solution you'd like Provide a function to enable human readable names for benchmark names. for powers of 2 and powers of 10.