tgamma(x) are not folded at the compilation time when (x) is constant

[fawdlstty]

Consider the following example.
https://godbolt.org/z/7aoPbzWEo

#include <cmath>

double f1() {
  return std::tgamma(3.0);
}

double f2() {
  return std::tgammaf(3.0f);
}

double f3() {
  return std::tgammal(3.0);
}