Remember to clear the cached data for the OptionValueFileSpec in SetValueFromCString.

<rdar://problem/16179718> target.expr-prefix contents appear to be cached for an entire session

llvm-svn: 205636

lldb/source/Interpreter/OptionValueFileSpec.cpp

@@ -99,6 +99,7 @@ OptionValueFileSpec::SetValueFromCString (const char *value_cstr,
 
             m_value_was_set = true;
             m_current_value.SetFile(filepath.c_str(), true);
+            m_data_sp.reset();
         }
         else
         {