ticket:10051 Mutexes and atomic ops, work in progress.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/andy@33656 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10050 Mutexes, Win32 fixes, work in progress.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/andy@33657 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10051 Mutex header file fixes, work in progress.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/andy@33658 251d0590-4201-4cf1-90de-194747b24ca1