Include #![feature(ptr_fn_addr_eq)] for non-nightly builds

Author: clin1234

src/impl_/pymethods.rs

@@ -21,10 +21,11 @@ use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::ptr::null_mut;
 
 #[cfg(feature = "nightly")]
-// #![feature(ptr_fn_addr_eq)]
+#![feature(ptr_fn_addr_eq)]
 use std::ptr::fn_addr_eq;
 
 #[cfg(not(feature = "nightly"))]
+#![feature(ptr_fn_addr_eq)]
 use std::marker::FnPtr;
 pub fn fn_addr_eq<T: FnPtr, U: FnPtr>(f: T, g: U) -> bool {
     f.addr() == g.addr()