std::pow implementation

[Richard Guenther]

> | The only sane possible semantics I see are:
> |
> | 1. inline declared functions are inlined always if technically possible
> | 2. the inline keyword has no effect
> | 3. inline is handled in an implementation defined manner (as stated in the
> |    standard), maybe by adjusting the set of functions considered for inlining,
> |    as gcc does.
>
> I'm arguing for #1 and #3 combined.  Meaning, inline simple functions
> at low optimization level, try hard at higher level + compiler
> parameter adjustement.

Thats what we have now - generally we go with #3, for small functions we
go with #1 (tune what is small with --param min-inline-insns=XXX).

Richard.