RFR: 8150720: Cleanup code around PrintOptoStatistics

[Vladimir Ivanov]

> While LogCompilation is diagnostic, Parse::print_statistics is the only
> place where any of the affected counters are printed out, and it's not
> defined in product binaries.
Yes, you are right. I missed that Compile::print_statics is empty in 
product binaries:
   static void print_statistics() PRODUCT_RETURN;

> If there's agreement that PrintOptoStatistics should be made diagnostic
> (or converted to UL) then I won't object, but if so I'd insist in
> wrapping the values in PerfCounters, since that makes them more useful
> as well as pads the values (haven't measured whether or not these cause
> any measurable false sharing, but global, non-atomically updated values
> do make me uneasy).
>
> I'd prefer pushing this as-is and follow-up on converting some or all
> counters to diagnostic separately, though.
I'm fine with removing unused counters, but I don't feel very 
comfortable with all these new macro usages.

So, I'd prefer to defer that part and clean it up when making 
PrintOptoStatistics diagnostics and converting the raw counters to 
PerfCounters.

Best regards,
Vladimir Ivanov