make getservby*_r return error code rather than -1 (and using errno)

[musl] / src / complex / csinf.c

#include "libm.h"

float complex csinf(float complex z)
{
        z = csinhf(cpackf(-cimagf(z), crealf(z)));
        return cpackf(cimagf(z), -crealf(z));
}