Add mutex interface

src/mutex.cpp

@@ -0,0 +1,20 @@
+#include <sta/mutex.hpp>
+
+
+namespace sta
+{
+	/**
+	 * @brief Dummy mutex implementation with no access control.
+	 */
+	class DummyMutex : public Mutex
+	{
+	public:
+		void acquire() override {}
+		void release() override {}
+	};
+
+	static DummyMutex dummyMutex;
+
+
+	Mutex * Mutex::ALWAYS_FREE = &dummyMutex;
+} // namespace sta