Fix TestDataFormatter* on Linux

[vharron]

Summary

llvm::StringRef doesn't make a copy of a string, it just holds a
reference. When special_directions_stream went out of scope,
special_directions was holding on to a stale pointer.

Moving special_directions_stream into a higher scope to keep
special_directions pointing to a valid string.

[vharron]

Committed revision 229767.

source/Core/FormatEntity.cpp

DumpValue (Stream &s,
     else
     {
         if (log)
             log->Printf("[Debugger::FormatPrompt] checking if I can handle as array");
         if (!is_array && !is_pointer)
             return false;
         if (log)
             log->Printf("[Debugger::FormatPrompt] handle as array");
+        StreamString special_directions_stream;
         llvm::StringRef special_directions;
         if (close_bracket_index != llvm::StringRef::npos && subpath.size() > close_bracket_index)
         {
             ConstString additional_data (subpath.drop_front(close_bracket_index+1));
-            StreamString special_directions_stream;
             special_directions_stream.Printf("${%svar%s",
                                              do_deref_pointer ? "*" : "",
                                              additional_data.GetCString());
 
             if (entry.fmt != eFormatDefault)
             {
                 const char format_char = FormatManager::GetFormatAsFormatChar(entry.fmt);
                 if (format_char != '\0')