1. renamed lib to to spitlog

2. Rotating bugfix

include/spitlog/details/null_mutex.h

@@ -0,0 +1,17 @@
+#pragma once
+
+// null, no cost mutex
+
+namespace spitlog {
+namespace details {
+struct null_mutex
+{
+    void lock() {}
+    void unlock() {}
+    bool try_lock()
+    {
+        return true;
+    }
+};
+}
+}