CoreMidi string release added to avoid memory leak.

RtMidi.cpp

@@ -801,6 +801,8 @@ static CFStringRef ConnectedEndpointName( MIDIEndpointRef endpoint )
   if ( anyStrings )
     return result;
 
+  CFRelease( result );
+
   // Here, either the endpoint had no connections, or we failed to obtain names 
   return EndpointName( endpoint, false );
 }