ticket:10799 ICU initialization code, review & cleanup.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35649 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10861 Fix several ICU4C compile warnings.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35650 251d0590-4201-4cf1-90de-194747b24ca1