Fix use of incomplete type in stdout sinks

include/spdlog/sinks/stdout_sinks.h

@@ -5,6 +5,7 @@
 
 #include "spdlog/details/console_globals.h"
 #include "spdlog/details/synchronous_factory.h"
+#include "spdlog/sinks/sink.h"
 #include <cstdio>
 
 namespace spdlog {