<rdar://problem/14071463>

SVN r189964 provided a sample Python script to inspect unordered(multi){set|map} with synthetic children, contribued by Jared Grubb
This checkin converts that sample script to a C++ provider built into LLDB
A test case is also provided



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@190564 91177308-0d34-0410-b5e6-96231b3b80d8