[lldb] Fix some warnings in the python plugin

lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h

@@ -130,7 +130,7 @@ template <typename T> T Take(PyObject *obj) {
   assert(!PyErr_Occurred());
   T thing(PyRefType::Owned, obj);
   assert(thing.IsValid());
-  return std::move(thing);
+  return thing;
 }
 
 // Retain a reference you have borrowed, and turn it into
@@ -148,7 +148,7 @@ template <typename T> T Retain(PyObject *obj) {
   assert(!PyErr_Occurred());
   T thing(PyRefType::Borrowed, obj);
   assert(thing.IsValid());
-  return std::move(thing);
+  return thing;
 }
 
 // This class can be used like a utility function to convert from

lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp

@@ -1190,6 +1190,7 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLineWithReturn(
     return true;
   }
   }
+  llvm_unreachable("Fully covered switch!");
 }
 
 Status ScriptInterpreterPythonImpl::ExecuteMultipleLines(