Build error const extern fn definitions are unstable.

[xiaoyuxlu]

Build failed.

error[E0658]: const extern fn definitions are unstable
Error: --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.127/src/macros.rs:188:17
|
188 | / pub $($constness)* unsafe extern fn $i($($arg: $argty),*
189 | | ) -> $ret {
190 | | $($body);*
191 | | }
| |_________________^
|
::: /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.127/src/unix/linux_like/mod.rs:1490:1
|
1490 | / f! {
1491 | | pub fn CMSG_FIRSTHDR(mhdr: *const msghdr) -> *mut cmsghdr {
1492 | | if (*mhdr).msg_controllen as usize >= ::mem::size_of::() {
1493 | | (*mhdr).msg_control as *mut cmsghdr
... |
1536 | | }
1537 | | }
| |_- in this macro invocation
|
= note: see issue #64926 rust-lang/rust#64926 for more information
= help: add #![feature(const_extern_fn)] to the crate attributes to enable
= note: this error originates in the macro f (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0658]: const extern fn definitions are unstable

[davidli2010]

const_extern_fn is stabilized in Rust 1.62.

[xiaoyuxlu]

Fixed #261