fix for Sun C++ 5.8

src/forwarder.cpp

@@ -33,4 +33,6 @@ int zmq::forwarder (socket_base_t *insocket_, socket_base_t *outsocket_)
         insocket_->recv (&msg, 0);
         outsocket_->send (&msg, 0);
     }
+
+    return 0;
 }

src/queue.cpp

@@ -94,5 +94,7 @@ int zmq::queue (class socket_base_t *insocket_,
             has_response = false;
         }
     }
+
+    return 0;
 }
 

src/streamer.cpp

@@ -33,4 +33,6 @@ int zmq::streamer (socket_base_t *insocket_, socket_base_t *outsocket_)
         insocket_->recv (&msg, 0);
         outsocket_->send (&msg, 0);
     }
+
+    return 0;
 }