Accept universal reference in PrintAndClearLogQueue (#30)

Author: cjappl

include/rtlog/rtlog.h

@@ -238,7 +238,7 @@ class Logger {
    * @return int The number of log messages that were processed and printed.
    */
   template <typename PrintLogFn>
-  int PrintAndClearLogQueue(PrintLogFn &printLogFn) {
+  int PrintAndClearLogQueue(PrintLogFn &&printLogFn) {
     int numProcessed = 0;
 
     InternalLogData value;