Add lgamma_r and lgammaf_r

[ankane]

For rust-lang/rust#99842 (comment)

Similar to #482

[ankane]

Note the signature is different from math.h - not exactly sure if that should be taken into account here or downstream for rust-lang/rust#99747.

[ankane]

Now thinking it may need to be taken into account here since the signature in cmath.rs will be:

pub fn lgamma_r(n: f64, s: &mut i32) -> f64;

[Amanieu]

The signature here should match the C one. You'll need to manually generate the wrapper function instead of using the no_mangle macro.

[ankane]

Thanks (again) @Amanieu. Updated to match the C signature.

[ankane]

Thanks!