ticket:10051: Mutex & InitOnce experiments, work in progress.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/andy@33469 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10051: Mutex & singleton experiments, resurrect Windows.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/andy@33470 251d0590-4201-4cf1-90de-194747b24ca1