[Bug libstdc++/80506] Wrong magic number in std::gamma_distribution

[emsr at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80506

--- Comment #3 from emsr at gcc dot gnu.org ---
I'm now of the opinion that we should push these down.
At least gcc-7.
That's what I'm doing with the specfun bits.