Start python3 compatibility
Start for #9660

These are changes to get vbench running under python3.  There are quite a few tests that need modification, but with these changes the code will parse and the suite can run (along with [vbench#36](https://github.com/pydata/vbench/pull/36)).

@rockg Really love you are working on this! Just wanted to mention that I put a consideration about this in the issue #9660 (but of course, that does not prevent us improving vbench as well, certainly on the short term).
 @rockg let's see if this can be fixed in 0.17.0; note that there are other PR's for using asv (but nice to fix this in the interim).
 closing as stale, but if you would like to reopen and fixup pls do.
