ticket:8464: Remove references to SharedPtr from public header file by subclassing Markus S. SharedObject class.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@34824 251d0590-4201-4cf1-90de-194747b24ca1
ticket:8464: Modify vcxproj files to add common/sharedobject.h and sharedobject.cpp

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@34825 251d0590-4201-4cf1-90de-194747b24ca1