Don't touch access timestamp when inferring type from path

[pmetras]

On Unix, when opening a file with std::fs::File::open(), the file is opened with O_RDONLY mode but the access timestamp in the file metadata is updated (see https://github.com/posborne/rust-systems-programming/blob/master/file-io.md and man 7 inode). In the case of infer, trying to infer a file type with infer::get_from_path should be without this side effect as it is on Windows where the file type can be deducted from the extension.

The way to do it is to open the file with the mode O_NOATIME, that can be done with the following code:

// We open the file without changing the access time in the metadata
let mode = (libc::O_RDONLY | libc::O_NOATIME).try_into().unwrap();
let mut file = OpenOptions::new().mode(mode).open(entry.path())?;

Please change infer::get_from_path to remove this side effect.