Drop old semaphore implementation

- Removed platform-specific implementations.
- Now all semaphores are in-object, unless they need to be conditionally created.
- Similarly to `Mutex`, provided a dummy implementation for when `NO_THREADS` is defined.
- Similarly to `Mutex`, methods are made `const` for easy use in such contexts.
- Language bindings updated: `wait()` and `post()` are now `void`.
- Language bindings updated: `try_wait()` added.

Bonus:
- Rewritten the `#ifdef` in `mutex.h` to meet the code style.

2 files changed, 14 insertions, 20 deletions

diff --git a/core/bind/core_bind.cpp b/core/bind/core_bind.cpp
index b798d732d6..0d8b75bb63 100644
--- a/core/bind/core_bind.cpp
+++ b/core/bind/core_bind.cpp
@@ -2576,30 +2576,26 @@ void _Marshalls::_bind_methods() {
 
 ////////////////
 
-Error _Semaphore::wait() {
+void _Semaphore::wait() {
 
-	return semaphore->wait();
+	semaphore.wait();
 }
 
-Error _Semaphore::post() {
+Error _Semaphore::try_wait() {
 
-	return semaphore->post();
+	return semaphore.try_wait() ? OK : ERR_BUSY;
 }
 
-void _Semaphore::_bind_methods() {
+void _Semaphore::post() {
 
-	ClassDB::bind_method(D_METHOD("wait"), &_Semaphore::wait);
-	ClassDB::bind_method(D_METHOD("post"), &_Semaphore::post);
+	semaphore.post();
 }
 
-_Semaphore::_Semaphore() {
-
-	semaphore = SemaphoreOld::create();
-}
-
-_Semaphore::~_Semaphore() {
+void _Semaphore::_bind_methods() {
 
-	memdelete(semaphore);
+	ClassDB::bind_method(D_METHOD("wait"), &_Semaphore::wait);
+	ClassDB::bind_method(D_METHOD("try_wait"), &_Semaphore::try_wait);
+	ClassDB::bind_method(D_METHOD("post"), &_Semaphore::post);
 }
 
 ///////////////
diff --git a/core/bind/core_bind.h b/core/bind/core_bind.h
index ae7c3d02fd..3a5bd28ce8 100644
--- a/core/bind/core_bind.h
+++ b/core/bind/core_bind.h
@@ -635,16 +635,14 @@ public:
 class _Semaphore : public Reference {
 
 	GDCLASS(_Semaphore, Reference);
-	SemaphoreOld *semaphore;
+	Semaphore semaphore;
 
 	static void _bind_methods();
 
 public:
-	Error wait();
-	Error post();
-
-	_Semaphore();
-	~_Semaphore();
+	void wait();
+	Error try_wait();
+	void post();
 };
 
 class _Thread : public Reference {