Const correct Thread class (#15741)

src/httpfetch.cpp

@@ -744,7 +744,7 @@ static void httpfetch_request_clear(u64 caller)
 bool httpfetch_sync_interruptible(const HTTPFetchRequest &fetch_request,
 		HTTPFetchResult &fetch_result, long interval)
 {
-	if (Thread *thread = Thread::getCurrentThread()) {
+	if (const Thread *thread = Thread::getCurrentThread()) {
 		HTTPFetchRequest req = fetch_request;
 		req.caller = httpfetch_caller_alloc_secure();
 		httpfetch_async(req);

src/threading/thread.cpp

@@ -164,7 +164,7 @@ bool Thread::wait()
 
 
 
-bool Thread::getReturnValue(void **ret)
+bool Thread::getReturnValue(void **ret) const
 {
 	if (m_running)
 		return false;

src/threading/thread.h

@@ -86,19 +86,19 @@ class Thread {
 	/*
 	 * Returns true if the calling thread is this Thread object.
 	 */
-	bool isCurrentThread() { return std::this_thread::get_id() == getThreadId(); }
+	bool isCurrentThread() const { return std::this_thread::get_id() == getThreadId(); }
 
-	bool isRunning() { return m_running; }
-	bool stopRequested() { return m_request_stop; }
+	bool isRunning() const { return m_running; }
+	bool stopRequested() const { return m_request_stop; }
 
-	std::thread::id getThreadId() { return m_thread_obj->get_id(); }
+	std::thread::id getThreadId() const { return m_thread_obj->get_id(); }
 
 	/*
 	 * Gets the thread return value.
 	 * Returns true if the thread has exited and the return value was available,
 	 * or false if the thread has yet to finish.
 	 */
-	bool getReturnValue(void **ret);
+	bool getReturnValue(void **ret) const;
 
 	/*
 	 * Binds (if possible, otherwise sets the affinity of) the thread to the
@@ -142,7 +142,7 @@ class Thread {
 	virtual void *run() = 0;
 
 private:
-	std::thread::native_handle_type getThreadHandle()
+	std::thread::native_handle_type getThreadHandle() const
 		{ return m_thread_obj->native_handle(); }
 
 	static void threadProc(Thread *thr);