java.nio.file: Remove support for FileStore information.

The API contract allows us to throw a SecurityException, so do
that unconditionally. Most processes on Android do not have
sufficient privileges to read mount information or to stat
mountpoints. This precludes us from implementing this API sensibly.

Also, make it clear that ACL / DOS and UserDefined file attribute
views are not supported. They require xattr support that may not
exist on our file systems. The tests were passing because they
silently bailed out.

Also, explicitly remove support for Dos / User and Acl based
FileAttributeViews. They are not supported, and were being dynamically
disabled at run time.

This removal is a step forward, except for an unfortunate wart in
the API; for some reason supportsFileAttributeView is a method in
the FileStore class, but getFileAttributeView is a method on the
FileSystemProvider class. This leaves callers without any method
to detect what AttributeViews a given file system provider supports,
but that should largely be irrelevant for most Android callers.

Bug: 36491936
Test: run cts -m CtsLibcoreOjTestCases, CtsLibcoreTestCases

Change-Id: I55cd191c52d15213c9f1d162d8f231733628ab75
9 files changed