musl: struct tcp_info: add new fields since 1.2.0/1.2.2

This reflects the upstream commits, 5e0c9f2 and d4f2981, which reflect
changes in linux 5.4 and 5.5 respectively

As mentioned in the comments, this is possible now as the CI musl version
has updated and the headers are newer.

(backport <rust-lang#4443>)
(cherry picked from commit fb4212a)

Author: xbjfk

libc-test/build.rs

@@ -4205,6 +4205,9 @@ fn test_linux(target: &str) {
             // FIXME(linux): Requires >= 6.4 kernel headers.
             "ptrace_sud_config" => true,
 
+            // Struct has changed for new musl versions
+            "tcp_info" if old_musl => true,
+
             _ => false,
         }
     });

src/unix/linux_like/linux/musl/mod.rs

@@ -323,16 +323,11 @@ s! {
         pub tcpi_probes: u8,
         pub tcpi_backoff: u8,
         pub tcpi_options: u8,
-        /*
-         * FIXME(musl): enable on all targets once musl headers are more up to date
-         */
         /// This contains the bitfields `tcpi_snd_wscale` and `tcpi_rcv_wscale`.
         /// Each is 4 bits.
-        #[cfg(target_arch = "loongarch64")]
         pub tcpi_snd_rcv_wscale: u8,
         /// This contains the bitfields `tcpi_delivery_rate_app_limited` (1 bit) and
         /// `tcpi_fastopen_client_fail` (2 bits).
-        #[cfg(target_arch = "loongarch64")]
         pub tcpi_delivery_fastopen_bitfields: u8,
         pub tcpi_rto: u32,
         pub tcpi_ato: u32,
@@ -378,10 +373,7 @@ s! {
         pub tcpi_bytes_retrans: u64,
         pub tcpi_dsack_dups: u32,
         pub tcpi_reord_seen: u32,
-        // FIXME(musl): enable on all targets once CI musl is updated
-        #[cfg(target_arch = "loongarch64")]
         pub tcpi_rcv_ooopack: u32,
-        #[cfg(target_arch = "loongarch64")]
         pub tcpi_snd_wnd: u32,
     }