Checks to see if a file is native to the platform.
A native file is one expressed in the platform-native filename format, e.g. "C:\Windows" or "/usr/bin/". This does not mean the file is local, as it might be on a locally mounted remote filesystem.
On some systems non-native files may be available using the native filesystem via a userspace filesystem (FUSE), in these cases this call will return false, but get_path will still return a native path.
This call does no blocking I/O.
true if this is native