only include windows.h when it's unavoidable

include/spdlog/sinks/win_eventlog_sink.h

@@ -30,6 +30,15 @@ Windows Registry Editor Version 5.00
 
 #pragma once
 
+#ifndef NOMINMAX
+#define NOMINMAX // prevent windows redefining min/max
+#endif
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+
+#include <windows.h>
 #include <winbase.h>
 
 #include <spdlog/details/null_mutex.h>