[lldb] Use C++11 default member initializers

This converts a default constructor's member initializers into C++11
default member initializers. This patch was automatically generated with
clang-tidy and the modernize-use-default-member-init check.

$ run-clang-tidy.py -header-filter='lldb' -checks='-*,modernize-use-default-member-init' -fix

This is a mass-refactoring patch and this commit will be added to
.git-blame-ignore-revs.

Differential revision: https://reviews.llvm.org/D103483

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

@@ -236,8 +236,7 @@ namespace {
 // save off initial state at the beginning, and restore it at the end
 struct InitializePythonRAII {
 public:
-  InitializePythonRAII()
-      : m_gil_state(PyGILState_UNLOCKED), m_was_already_initialized(false) {
+  InitializePythonRAII() {
     InitializePythonHome();
 
 #ifdef LLDB_USE_LIBEDIT_READLINE_COMPAT_MODULE
@@ -357,8 +356,8 @@ private:
   }
 
   TerminalState m_stdin_tty_state;
-  PyGILState_STATE m_gil_state;
-  bool m_was_already_initialized;
+  PyGILState_STATE m_gil_state = PyGILState_UNLOCKED;
+  bool m_was_already_initialized = false;
 };
 } // namespace