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/Target/ThreadPlanStepOverRange.cpp b/lldb/source/Target/ThreadPlanStepOverRange.cpp
index 2ded595..c8fd6f9 100644
--- a/lldb/source/Target/ThreadPlanStepOverRange.cpp
+++ b/lldb/source/Target/ThreadPlanStepOverRange.cpp
@@ -422,7 +422,7 @@
                   "Stepping over inlined function \"%s\" in inlined stack: ",
                   name);
               DumpRanges(&s);
-              log->PutCString(s.GetData());
+              log->PutString(s.GetString());
             }
           }
         }