[libstdc++] numeric_limits: integer parameters

[Gabriel Dos Reis]

Richard Henderson <rth@twiddle.net> writes:

| Removes a whole lot of hard-coding in favour of computation.
| Fortunately, unlike in limits.h, none of this has to be 
| accessible to the preprocessor, so we can let the compiler
| do constant folding with types.
| 
| Ok?

Yes.

-- Gaby