math: raise invalid flag in ilogb*.c on +-0, +-inf and nan

[musl] / src / math / tgamma.c

#include <math.h>

// FIXME: use lanczos approximation

double __lgamma_r(double, int *);

double tgamma(double x)
{
        int sign;
        double y;

        y = exp(__lgamma_r(x, &sign));
        if (sign < 0)
                y = -y;
        return y;
}