math.log() benchmark of first 1 billion int using std.parallelism

[Iov Gherman via Digitalmars-d-learn]

> That's very different to my results.
>
> I see no important difference between ldc and dmd when using 
> std.math, but when using core.stdc.math ldc halves its time 
> where dmd only manages to get to ~80%

I checked again today and the results are interesting, on my pc I 
don't see any difference between std.math and core.stdc.math with 
ldc. Here are the results with all compilers.

- with std.math:
dmd: 4 secs, 878 ms
ldc: 5 secs, 650 ms
gdc: 9 secs, 161 ms

- with core.stdc.math:
dmd: 5 secs, 991 ms
ldc: 5 secs, 572 ms
gdc: 7 secs, 957 ms