Don't allow direct access to StreamString's internal buffer.

This is a large API change that removes the two functions from
StreamString that return a std::string& and a const std::string&,
and instead provide one function which returns a StringRef.

Direct access to the underlying buffer violates the concept of
a "stream" which is intended to provide forward only access,
and makes porting to llvm::raw_ostream more difficult in the
future.

Differential Revision: https://reviews.llvm.org/D26698

llvm-svn: 287152
diff --git a/lldb/source/Symbol/ObjectFile.cpp b/lldb/source/Symbol/ObjectFile.cpp
index a89ebfb..0b1d6b2 100644
--- a/lldb/source/Symbol/ObjectFile.cpp
+++ b/lldb/source/Symbol/ObjectFile.cpp
@@ -646,5 +646,5 @@
   ConstString file_name = GetModule()->GetFileSpec().GetFilename();
   ss.Printf("___lldb_unnamed_symbol%u$$%s", ++m_synthetic_symbol_idx,
             file_name.GetCString());
-  return ConstString(ss.GetData());
+  return ConstString(ss.GetString());
 }