musl: add renameat2 binding

libc-test/build.rs

@@ -4633,6 +4633,8 @@ fn test_linux(target: &str) {
             "preadv2" | "pwritev2" if musl => true,
             // FIXME(musl): Supported in new musl but we don't have a new enough version in CI.
             "statx" if musl => true,
+            // FIXME(musl): Supported since musl 1.2.6 but not yet in CI.
+            "renameat2" if musl => true,
 
             // Needs glibc 2.33 or later.
             "mallinfo2" => true,

libc-test/semver/linux-musl.txt

@@ -86,6 +86,7 @@ pututxline
 pwritev2
 pwritev64
 reallocarray
+renameat2
 setutxent
 tcp_info
 timex

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

@@ -795,6 +795,13 @@ extern "C" {
         flags: c_int,
     ) -> ssize_t;
     pub fn getauxval(type_: c_ulong) -> c_ulong;
+    pub fn renameat2(
+        olddirfd: c_int,
+        oldpath: *const c_char,
+        newdirfd: c_int,
+        newpath: *const c_char,
+        flags: c_uint,
+    ) -> c_int;
 
     // Added in `musl` 1.1.20
     pub fn explicit_bzero(s: *mut c_void, len: size_t);