remove go-msgpack from benchmarks

go-msgpack has been stalled and has been deprecated for over a year. 
The code was moved into go-codec and all development continued there. 
It should not be reflected in this benchmark.

Also, use AsSymbolNone for Binc. 
Binc is either optimized for space (de-duplicate strings) or speed (do not de-duplicate strings). 
For performance comparisons, do not de-duplicate strings; this is in line with most other impls.