Removed include null_mutex.h from common.h

include/spdlog/common.h

@@ -15,7 +15,6 @@
 #include <string>
 #include <type_traits>
 
-#include "details/null_mutex.h"
 #include "source_loc.h"
 #include "tweakme.h"
 

include/spdlog/sinks/stdout_sinks.h

@@ -6,6 +6,7 @@
 #include <cstdio>
 
 #include "../details/synchronous_factory.h"
+#include "../details/null_mutex.h"
 #include "base_sink.h"
 #include "sink.h"
 

src/sinks/base_sink.cpp

@@ -8,6 +8,7 @@
 
 #include "spdlog/common.h"
 #include "spdlog/pattern_formatter.h"
+#include "spdlog/details/null_mutex.h"
 
 template <typename Mutex>
 spdlog::sinks::base_sink<Mutex>::base_sink()