fix(flock): check if they are marked unsupported in libstd

Before this Cargo invokes syscalls and check whether it gets ENOTSUP to
determine flock is unsupported. However, now the "unsupported platforms"
are pre-defined by libstd [1]. Cargo should perhaps return unsupported
if a platform is marked unsupported by libstd.

Without this, some people on Termux may be affected I guess?

[1]: https://github.com/rust-lang/rust/blob/e9b6085088fd671ecfbe4cbebe1d26796d8bfa30/library/std/src/sys/fs/unix.rs#L1395-L1410

Author: weihanglo

src/cargo/util/flock.rs

@@ -353,8 +353,9 @@ fn try_acquire(path: &Path, lock_try: &dyn Fn() -> Result<(), TryLockError>) ->
         Ok(()) => Ok(true),
 
         // In addition to ignoring NFS which is commonly not working we also
-        // just ignore locking on filesystems that look like they don't
-        // implement file locking.
+        // just ignore locking on filesystems that either are marked unsupported
+        // by libstd, or look like they don't implement file locking.
+        Err(TryLockError::Error(e)) if e.kind() == std::io::ErrorKind::Unsupported => Ok(true),
         Err(TryLockError::Error(e)) if error_unsupported(&e) => Ok(true),
 
         Err(TryLockError::Error(e)) => {