Find MountInfo properly when symlink is used

[kropacf]

Fixes #4607

According to GNU implementation the entered path is being compared with the canonicalized device name
in MountInfo.

[sylvestre]

On windows, it fails with :

---- filesystem::tests::mount_info_from_path::test_dev_name_match stdout ----
thread 'filesystem::tests::mount_info_from_path::test_dev_name_match' panicked at 'called `Option::unwrap()` on a `None` value', src\uu\df\src\filesystem.rs:230:73
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library\std\src\panicking.rs:584
   1: core::panicking::panic_fmt
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library\core\src\panicking.rs:142
   2: core::panicking::panic
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library\core\src\panicking.rs:48
   3: enum$<core::option::Option<ref$<uucore::features::fsext::MountInfo> >, 1, 18446744073709551615, Some>::unwrap<ref$<uucore::features::fsext::MountInfo> >
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52\library\core\src\option.rs:775
   4: uu_df::filesystem::tests::mount_info_from_path::test_dev_name_match
             at .\src\filesystem.rs:230
   5: uu_df::filesystem::tests::mount_info_from_path::test_dev_name_match::closure$0
             at .\src\filesystem.rs:223
   6: core::ops::function::FnOnce::call_once<uu_df::filesystem::tests::mount_info_from_path::test_dev_name_match::closure_env$0,tuple$<> >
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52\library\core\src\ops\function.rs:248
   7: core::ops::function::FnOnce::call_once
             at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library\core\src\ops\function.rs:248
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/ls/sort-width-option. tests/ls/sort-width-option is passing on 'main'. Maybe you have to rebase?

[sylvestre]

thanks!