[Bug libstdc++/70299] pow(long double, int) gives more imprecise result than pow(long double,long double) in c++03 mode

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70299

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-03-18
          Component|c++                         |libstdc++
     Ever confirmed|0                           |1

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The GCC docs for __builtin_powil says "Unlike the pow function no guarantees
about precision and rounding are made."

So I suppose we should switch the C++03 pow(floating-point-type, int) functions
to use a better built-in.