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/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
index 77b9fc8..e3842e1 100644
--- a/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
+++ b/lldb/source/Plugins/Process/MacOSX-Kernel/ProcessKDP.cpp
@@ -965,7 +965,7 @@
                 packet.PutBytesAsRawHex8(
                     reply.GetDataStart(), reply.GetByteSize(),
                     endian::InlHostByteOrder(), endian::InlHostByteOrder());
-                result.AppendMessage(packet.GetString().c_str());
+                result.AppendMessage(packet.GetString());
                 result.SetStatus(eReturnStatusSuccessFinishResult);
                 return true;
               } else {