[PATCH] Fix PR11706, use __builtin_powi[lf] for pow(x, int)

[Paolo Carlini]

Richard Guenther wrote:

>Indeed.  Weird that didn't show up during testing.  Grep'ing for
>cmath.tcc also didn't show it because complex doesn't include it.
>
>I'll re-test the following (very) simpler patch then.  Ok if
>testing succeeds?
>  
>
Well, after the patch for 19402 is in, I suppose... ;)

Seriously, I think we all agree that this is the way we want to go, but
let's wait for Gaby's comments (while 19402 is finally reviewed).

Paolo.