Fix sizeof usage for Variant pointers in alloca

Coverity report this as a non portable usage of sizeof

core/variant/callable_bind.cpp

@@ -133,7 +133,7 @@ void CallableCustomBind::get_bound_arguments(Vector<Variant> &r_arguments, int &
 }
 
 void CallableCustomBind::call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, Callable::CallError &r_call_error) const {
-	const Variant **args = (const Variant **)alloca(sizeof(const Variant **) * (binds.size() + p_argcount));
+	const Variant **args = (const Variant **)alloca(sizeof(Variant *) * (binds.size() + p_argcount));
 	for (int i = 0; i < p_argcount; i++) {
 		args[i] = (const Variant *)p_arguments[i];
 	}
@@ -145,7 +145,7 @@ void CallableCustomBind::call(const Variant **p_arguments, int p_argcount, Varia
 }
 
 Error CallableCustomBind::rpc(int p_peer_id, const Variant **p_arguments, int p_argcount, Callable::CallError &r_call_error) const {
-	const Variant **args = (const Variant **)alloca(sizeof(const Variant **) * (binds.size() + p_argcount));
+	const Variant **args = (const Variant **)alloca(sizeof(Variant *) * (binds.size() + p_argcount));
 	for (int i = 0; i < p_argcount; i++) {
 		args[i] = (const Variant *)p_arguments[i];
 	}

scene/animation/animation_mixer.cpp

@@ -1789,7 +1789,7 @@ void AnimationMixer::_blend_apply() {
 
 void AnimationMixer::_call_object(Object *p_object, const StringName &p_method, const Vector<Variant> &p_params, bool p_deferred) {
 	// Separate function to use alloca() more efficiently
-	const Variant **argptrs = (const Variant **)alloca(sizeof(const Variant **) * p_params.size());
+	const Variant **argptrs = (const Variant **)alloca(sizeof(Variant *) * p_params.size());
 	const Variant *args = p_params.ptr();
 	uint32_t argcount = p_params.size();
 	for (uint32_t i = 0; i < argcount; i++) {