[Prelim patch] Speed up ints parsing

[Paolo Carlini]

Paolo Carlini wrote:

> 3.4
> ---
> 18.740u 0.030s 0:19.59 95.8%    0+0k 0+0io 208pf+0w
>
> 3.4 + this patch
> ----------------
> 9.940u 0.030s 0:10.40 95.8%     0+0k 0+0io 197pf+0w

By the way, for comparison:

3.3.2
-----
32.820u 0.030s 0:33.98 96.6%    0+0k 0+0io 215pf+0w


So, we are making progress, after all... ;)

Paolo.