[Patch] Fix istream::ignore + minor things

[Paolo Carlini]

Damour, James A wrote:

>Would your ignore code benefit from using __builtin_expect (see example
>below)?
>
>-          if (__n != numeric_limits<streamsize>::max())
>+          if (__builtin_expect(__n !=
>numeric_limits<streamsize>::max(),1))
>  
>
Thanks for the suggestion. The evidence about the benefits of 
__builtin_expect is actually rather thin, however. You may find various 
discussions about this topics on the lists.

The code is in flux, anyway, I have yet to provide the performance 
improvement that I promised, which now (after having fixed the 
conformance issue) is becoming quite clear. Expect something by the end 
of the week.

By the way, are you willing to benchmark on a machine of your choice the 
impact of __builtin_expect??

Thanks,
Paolo.