Update notes for submitted changes

* ICU4C updated to version 53, including new data and revised collation with better performance.
Update notes for submitted changes

* Remove unused LOCAL_LDLIBS.
Update notes for submitted changes

* Don't factor out make variables that are only used once for the host.
Update notes for submitted changes

* Removing data hacks from ICU root.txt
Update notes for submitted changes

* Fix ICU tests