Fix ref-leak in LLDBSwigPythonCallPythonLogOutputCallback

[luyer]

Summary

Fix ref-leak in LLDBSwigPythonCallPythonLogOutputCallback: as with almost all functions returning PyObject*, the caller receives a new reference and must DECREF it if they want to ignore it. In this case, errors are silently ignored in the current code, so use XDECREF (null-safe).

[zturner]

lgtm, thanks! In the future please add llvm-commits to the subscribers list. Do you have commit access?

[luyer]

No, I don't believe I have commit access.

llvmRefLeak/google3/third_party/llvm/llvm/tools/lldb/scripts/Python/python-wrapper.swig

 void LLDBSwigPythonCallPythonLogOutputCallback(const char *str, void *baton) {
     if (baton != Py_None) {
       SWIG_PYTHON_THREAD_BEGIN_BLOCK;
-      PyObject_CallFunction(reinterpret_cast<PyObject*>(baton), const_cast<char*>("s"), str);
+      PyObject* result = PyObject_CallFunction(
+        reinterpret_cast<PyObject*>(baton), const_cast<char*>("s"), str);
+      Py_XDECREF(result);
       SWIG_PYTHON_THREAD_END_BLOCK;
     }
 }