xfs: report crtime and attribute flags to statx

statx has the ability to report inode creation times and inode flags, so
hook up di_crtime and di_flags to that functionality.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>