Factor out SONAR_LOG

Reviewed By: passy

Differential Revision: D9555739

fbshipit-source-id: 022763ea03047e1c4cd88d5f389b66be4cbe416b

xplat/Sonar/Log.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <string>
+
+namespace facebook {
+namespace sonar {
+
+  void log(const std::string& message);
+
+} // namespace sonar
+} // namespace facebook