Fixes in the IRInterpreter:

- removed an unnecessary variable
- fixed an issue where we sometimes
  wrote too much data into a buffer
- made the recognition of variables
  as "this" a little more conservative

<rdar://problem/13216268>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@175318 91177308-0d34-0410-b5e6-96231b3b80d8
NSSet formatter is now C++ code
Split some NS* formatters in their own source files
Refactored a utility function for the C++ formatters to use
Fixed the skip-summary test case to be explicit about requiring libstdc++ for operation



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@175323 91177308-0d34-0410-b5e6-96231b3b80d8