util: BlackholeLogger, a quiet Logger drop-in replacement

The compiler should be able to completely optimize away side-effect
free usage of this logger.  Can be used as a drop-in replacement for
Loggers to silence logging output for known-good code without having
to remove the corresponding "LOG << ..." code.

Change-Id: Ifb276223f61686773dd6108aafd567e99c88b223

src/core/util/BlackholeLogger.hpp

@@ -0,0 +1,25 @@
+#ifndef __BLACKHOLE_LOGGER_HPP__
+#define __BLACKHOLE_LOGGER_HPP__
+
+#include <iostream>
+
+namespace fail {
+
+/**
+ * \class BlackholeLogger
+ * A /dev/null sink as a drop-in replacement for Logger.  Should be completely
+ * optimized away on non-trivial optimization levels.
+ */
+class BlackholeLogger {
+public:
+	Logger(const std::string& description = "Fail*", bool show_time = true,
+		   std::ostream& dest = std::cout) { }
+	void setDescription(const std::string& descr) { }
+	void showTime(bool choice) { }
+	template<class T>
+	inline std::ostream& operator <<(const T& v) { }
+};
+
+} // end-of-namespace: fail
+
+#endif // __BLACKHOLE_LOGGER_HPP__