Use libc::accept4 on Android instead of raw syscall.

Author: de-vri-es

library/std/src/sys/unix/net.rs

@@ -195,6 +195,7 @@ impl Socket {
         // glibc 2.10 and musl 0.9.5.
         cfg_if::cfg_if! {
             if #[cfg(any(
+                target_os = "android",
                 target_os = "dragonfly",
                 target_os = "freebsd",
                 target_os = "illumos",
@@ -206,13 +207,6 @@ impl Socket {
                     libc::accept4(self.0.raw(), storage, len, libc::SOCK_CLOEXEC)
                 })?;
                 Ok(Socket(FileDesc::new(fd)))
-            // While the Android kernel supports the syscall,
-            // it is not included in all versions of Android's libc.
-            } else if #[cfg(target_os = "android")] {
-                let fd = cvt_r(|| unsafe {
-                    libc::syscall(libc::SYS_accept4, self.0.raw(), storage, len, libc::SOCK_CLOEXEC)
-                })?;
-                Ok(Socket(FileDesc::new(fd as c_int)))
             } else {
                 let fd = cvt_r(|| unsafe { libc::accept(self.0.raw(), storage, len) })?;
                 let fd = FileDesc::new(fd);