haiku adding accept4 posix call

[ref](haiku/haiku@6beff0d)

Author: devnexen

src/unix/haiku/mod.rs

@@ -1779,6 +1779,13 @@ extern "C" {
         address_len: crate::socklen_t,
     ) -> c_int;
 
+    pub fn accept4(
+        socket: c_int,
+        address: *mut crate::sockaddr,
+        addressLength: *mut crate::socklen_t,
+        flags: c_int,
+    ) -> c_int;
+
     pub fn writev(fd: c_int, iov: *const crate::iovec, count: c_int) -> ssize_t;
     pub fn readv(fd: c_int, iov: *const crate::iovec, count: c_int) -> ssize_t;