Modernize Thread

- Based on C++11's `thread` and `thread_local`
- No more need to allocate-deallocate or check for null
- No pointer anymore, just a member variable
- Platform-specific implementations no longer needed (except for the few cases of non-portable functions)
- Simpler for `NO_THREADS`
- Thread ids are now the same across platforms (main is 1; others follow)

platform/javascript/audio_driver_javascript.cpp

@@ -267,7 +267,7 @@ int AudioDriverJavaScript::WorkletNode::create(int p_buffer_size, int p_channels
 
 void AudioDriverJavaScript::WorkletNode::start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) {
 	godot_audio_worklet_start(p_in_buf, p_in_buf_size, p_out_buf, p_out_buf_size, state);
-	thread = Thread::create(_audio_thread_func, this);
+	thread.start(_audio_thread_func, this);
 }
 
 void AudioDriverJavaScript::WorkletNode::lock() {
@@ -280,8 +280,6 @@ void AudioDriverJavaScript::WorkletNode::unlock() {
 
 void AudioDriverJavaScript::WorkletNode::finish() {
 	quit = true; // Ask thread to quit.
-	Thread::wait_to_finish(thread);
-	memdelete(thread);
-	thread = nullptr;
+	thread.wait_to_finish();
 }
 #endif

platform/javascript/audio_driver_javascript.h

@@ -59,7 +59,7 @@ public:
 			STATE_MAX,
 		};
 		Mutex mutex;
-		Thread *thread = nullptr;
+		Thread thread;
 		bool quit = false;
 		int32_t state[STATE_MAX] = { 0 };
 

platform/javascript/export/export.cpp

@@ -213,7 +213,7 @@ class EditorExportPlatformJavaScript : public EditorExportPlatform {
 	Ref<EditorHTTPServer> server;
 	bool server_quit = false;
 	Mutex server_lock;
-	Thread *server_thread = nullptr;
+	Thread server_thread;
 
 	enum ExportMode {
 		EXPORT_MODE_NORMAL = 0,
@@ -681,7 +681,7 @@ void EditorExportPlatformJavaScript::_server_thread_poll(void *data) {
 
 EditorExportPlatformJavaScript::EditorExportPlatformJavaScript() {
 	server.instance();
-	server_thread = Thread::create(_server_thread_poll, this);
+	server_thread.start(_server_thread_poll, this);
 
 	Ref<Image> img = memnew(Image(_javascript_logo));
 	logo.instance();
@@ -702,8 +702,7 @@ EditorExportPlatformJavaScript::EditorExportPlatformJavaScript() {
 EditorExportPlatformJavaScript::~EditorExportPlatformJavaScript() {
 	server->stop();
 	server_quit = true;
-	Thread::wait_to_finish(server_thread);
-	memdelete(server_thread);
+	server_thread.wait_to_finish();
 }
 
 void register_javascript_exporter() {