Quick fix for the libc++ std::map synthetic children provider
If you try to access any child > 0 without having touched child 0, LLDB won't be able to reconstruct type information from the debug info.
Previously, we would fail.
Now, we simply go fetch child 0 and then come back.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@174795 91177308-0d34-0410-b5e6-96231b3b80d8