libct/system/xattrs: remove

This is not used since commit 5e7b48f7c0 (23 Mar 2017).

In case there are external users, they should switch to
opencontainers/selinux.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/system/xattrs_linux.go

@@ -1,36 +0,0 @@
-package system
-
-import "golang.org/x/sys/unix"
-
-// Returns a []byte slice if the xattr is set and nil otherwise
-// Requires path and its attribute as arguments
-func Lgetxattr(path string, attr string) ([]byte, error) {
-	var sz int
-	// Start with a 128 length byte array
-	dest := make([]byte, 128)
-	sz, errno := unix.Lgetxattr(path, attr, dest)
-
-	//nolint:errorlint // unix errors are bare
-	switch {
-	case errno == unix.ENODATA:
-		return nil, errno
-	case errno == unix.ENOTSUP:
-		return nil, errno
-	case errno == unix.ERANGE:
-		// 128 byte array might just not be good enough,
-		// A dummy buffer is used to get the real size
-		// of the xattrs on disk
-		sz, errno = unix.Lgetxattr(path, attr, []byte{})
-		if errno != nil {
-			return nil, errno
-		}
-		dest = make([]byte, sz)
-		sz, errno = unix.Lgetxattr(path, attr, dest)
-		if errno != nil {
-			return nil, errno
-		}
-	case errno != nil:
-		return nil, errno
-	}
-	return dest[:sz], nil
-}