SPY-195: Defer String Concat in handleEmptySelects()

MemcachedConnection.handleEmptySelects() has a debug level log
statement that doesn't correctly defer the concatentation of
the argument until it has determined that the level is enabled.

Change-Id: I3c8bb70cfaa9f47eb790f2eb150bacca2ce839b6
Reviewed-on: http://review.couchbase.org/76567
Reviewed-by: Michael Nitschinger <michael@nitschinger.at>
Tested-by: Michael Nitschinger <michael@nitschinger.at>

Author: amcrn

src/main/java/net/spy/memcached/MemcachedConnection.java

@@ -499,8 +499,8 @@ private void handleOperationalTasks() throws IOException {
    * Helper method for {@link #handleIO()} to handle empty select calls.
    */
   private void handleEmptySelects() {
-    getLogger().debug("No selectors ready, interrupted: "
-      + Thread.interrupted());
+    getLogger().debug("No selectors ready, interrupted: %b",
+      Thread.interrupted());
 
     if (++emptySelects > DOUBLE_CHECK_EMPTY) {
       for (SelectionKey sk : selector.keys()) {