ticket:10373: fix -DU_USING_ICU_NAMESPACE=0 issues

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@34251 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10365: fix namespace issue: icu::UInitOnce

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@34252 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10373: Fix ambiguous names build problem from previous namesapce change.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@34253 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10373 One more namespace fix.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@34254 251d0590-4201-4cf1-90de-194747b24ca1