Correct back JackAlsaDriver::Read method

git-svn-id: http://subversion.jackaudio.org/jack/jack2/trunk/jackmp@1422 0c269be4-1314-0410-8aa9-9f06e86f4224

linux/alsa/JackAlsaDriver.cpp

@@ -2215,8 +2215,8 @@ int JackAlsaDriver::Read()
         JackLog("ALSA XRun \n");
         //NotifyXRun(jack_get_microseconds());
         NotifyXRun(fLastWaitUst);
-        return 0;
-        //return -1;
+        //return 0;
+        return -1;
     }
 
     //fLastWaitUst = GetMicroSeconds(); // Take callback date here