UPSTREAM: unicode: Don't special case ignorable code points

We don't need to handle them separately. Instead, just let them
decompose/casefold to themselves.

Change-Id: I01c3f2c98ae4d84269586cec09f18239cbee0abb
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
(cherry picked from commit 5c26d2f1)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Signed-off-by: Lee Jones <joneslee@google.com>