ticket:9101: builder lookup of CEs from NFD text, some cleanup

git-svn-id: http://source.icu-project.org/repos/icu/icu@33617 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10051: initOnce and Mutex, work in progress.

git-svn-id: http://source.icu-project.org/repos/icu/icu@33618 251d0590-4201-4cf1-90de-194747b24ca1