Fix race condition in LimitedWaitable between Notify and Wait

Common/Thread/Event.h

@@ -12,8 +12,8 @@ public:
 	}
 
 	void Wait() override {
+		std::unique_lock<std::mutex> lock;
 		if (!triggered_) {
-			std::unique_lock<std::mutex> lock;
 			cond_.wait(lock, [&] { return triggered_.load(); });
 		}
 	}

Common/Thread/Waitable.h

@@ -12,18 +12,18 @@ public:
 	}
 
 	void Wait() override {
+		std::unique_lock<std::mutex> lock(mutex_);
 		if (!triggered_) {
-			std::unique_lock<std::mutex> lock(mutex_);
 			cond_.wait(lock, [&] { return triggered_.load(); });
 		}
 	}
 
 	bool WaitFor(double budget) {
 		uint32_t us = budget > 0 ? (uint32_t)(budget * 1000000.0) : 0;
+		std::unique_lock<std::mutex> lock(mutex_);
 		if (!triggered_) {
 			if (us == 0)
 				return false;
-			std::unique_lock<std::mutex> lock(mutex_);
 			cond_.wait_for(lock, std::chrono::microseconds(us), [&] { return triggered_.load(); });
 		}
 		return triggered_;