musl: aarch64: update type of ipc_perm->__seq to match upstream

The architecture-specific definitions was removed in upstream commit
319b2d0, changing the type to the generic definition of int.

Author: xbjfk

libc-test/build.rs

@@ -3648,7 +3648,6 @@ fn test_linux(target: &str) {
     let x32 = target.contains("x32");
     let x86_32 = target.contains("i686");
     let x86_64 = target.contains("x86_64");
-    let aarch64_musl = aarch64 && musl;
     let gnueabihf = target.contains("gnueabihf");
     let x86_64_gnux32 = target.contains("gnux32") && x86_64;
     let riscv64 = target.contains("riscv64");
@@ -4739,8 +4738,8 @@ fn test_linux(target: &str) {
             "sched_ss_init_budget",
             "sched_ss_max_repl",
         ].contains(&field) && musl) ||
-        // FIXME(musl): After musl 1.1.24, the type becomes `int` instead of `unsigned short`.
-        (struct_ == "ipc_perm" && field == "__seq" && aarch64_musl) ||
+        // After musl 1.1.24, the type becomes `int` instead of `unsigned short`.
+        (struct_ == "ipc_perm" && field == "__seq" && old_musl && aarch64) ||
         // glibc uses unnamed fields here and Rust doesn't support that yet
         (struct_ == "timex" && field.starts_with("__unused")) ||
         // FIXME(linux): It now takes mode_t since glibc 2.31 on some targets.

src/unix/linux_like/linux/musl/b64/aarch64/mod.rs

@@ -78,9 +78,22 @@ s! {
         pub cuid: crate::uid_t,
         pub cgid: crate::gid_t,
         pub mode: crate::mode_t,
+
+        #[cfg(musl_v1_2_3)]
+        pub __seq: c_int,
+        #[cfg(not(musl_v1_2_3))]
+        #[deprecated(
+            since = "0.2.173",
+            note = "The type of this field has changed from c_ushort to c_int, \
+                we'll follow that change in the future release as part of \
+                an effort to update the API to newer musl versions. \
+                You can test these changes now by setting the \
+                RUST_LIBC_UNSTABLE_MUSL_1_2_3 environment variable \
+                when building. See #4443 for more info."
+        )]
         pub __seq: c_ushort,
-        __unused1: c_ulong,
-        __unused2: c_ulong,
+        __unused1: c_long,
+        __unused2: c_long,
     }
 
     pub struct ucontext_t {