Catch EOPNOTSUPP as failure for opportunistic flags

quinn-udp/src/unix.rs

@@ -1018,7 +1018,7 @@ mod gro {
 /// Returns whether the given socket option is supported on the current platform
 ///
 /// Yields `Ok(true)` if the option was set successfully, `Ok(false)` if setting
-/// the option raised an `ENOPROTOOPT` error, and `Err` for any other error.
+/// the option raised an `ENOPROTOOPT` or `EOPNOTSUPP` error, and `Err` for any other error.
 fn set_socket_option_supported(
     socket: &impl AsRawFd,
     level: libc::c_int,
@@ -1028,6 +1028,7 @@ fn set_socket_option_supported(
     match set_socket_option(socket, level, name, value) {
         Ok(()) => Ok(true),
         Err(err) if err.raw_os_error() == Some(libc::ENOPROTOOPT) => Ok(false),
+        Err(err) if err.raw_os_error() == Some(libc::EOPNOTSUPP) => Ok(false),
         Err(err) => Err(err),
     }
 }