more code cleanup

include/c11log/sinks/async_sink.h

@@ -39,7 +39,7 @@ protected:
     void _thread_loop();
 
 private:
-    c11log::logger::sinks_vector_t _sinks;
+    std::vector<std::shared_ptr<sink>> _sinks;
     std::atomic<bool> _active;
     q_type _q;
     std::thread _back_thread;

include/c11log/sinks/null_sink.h

@@ -1,6 +1,8 @@
 #pragma once
-
+#include <mutex>
 #include "base_sink.h"
+#include "../details/null_mutex.h"
+
 
 namespace c11log {
 namespace sinks {
@@ -13,6 +15,9 @@ protected:
     {}
 };
 
+typedef null_sink<details::null_mutex> null_sink_st;
+typedef null_sink<std::mutex> null_sink_mt;
+
 }
 }