[PATCH] Make the _gfortran_pow* const

[Jerry DeLisle]

Andrew Pinski wrote:
> Hi,
>   This patch makes the _gfortran_pow* function constant functions as the
> return value is only dependent on those values and they don't have any
> special side effects.
> 
> This patch speeds up my father's code by about 10% where he has a couple
> of rd**3.
> 
> OK? Bootstrapped and tested on i686-linux-gnu with no regressions.
> 
OK, also reg tested on x86-64