Make set_times public

[tertsdiepraam]

Hi! I have a use case¹ where both the atime and mtime are optional and where following the symlink is optional. While looking through the source code of this crate, I found this function in the unix-specific part of the library, which fits my use case perfectly, but it's not public:

filetime/src/unix/linux.rs

Lines 87 to 92 in 5eec5a5

	fn set_times(
	p: &Path,
	atime: Option<FileTime>,
	mtime: Option<FileTime>,
	symlink: bool,
	) -> io::Result<()> {

Similar functions do not yet exist for the Windows and Redox implementations, but I think those could be added with relatively little effort.

If you decide to expose this, I'd recommend a name like set_path_times, mirroring the set_file_handle_times name, which is very similar in functionality. I would be happy to open a PR for this.

This would also partially fix #83, albeit not in the most elegant way.

Footnotes

1. The touch utility of uutils, which basically acts as a wrapper around the utimensat syscall and therefore requires the same flexibility. ↩