Remove unnecessary casts

src/pgm_socket.cpp

@@ -454,7 +454,7 @@ size_t zmq::pgm_socket_t::send (unsigned char *data_, size_t data_len_)
     //  We have to write all data as one packet.
     if (nbytes > 0) {
         zmq_assert (status == PGM_IO_STATUS_NORMAL);
-        zmq_assert ((ssize_t) nbytes == (ssize_t) data_len_);
+        zmq_assert (nbytes == data_len_);
     } else {
         zmq_assert (status == PGM_IO_STATUS_RATE_LIMITED ||
             status == PGM_IO_STATUS_WOULD_BLOCK);

src/stream_engine.cpp

@@ -302,7 +302,7 @@ int zmq::stream_engine_t::write (const void *data_, size_t size_)
         return -1;
 
     wsa_assert (nbytes != SOCKET_ERROR);
-    return (size_t) nbytes;
+    return nbytes;
 
 #else
 
@@ -354,7 +354,7 @@ int zmq::stream_engine_t::read (void *data_, size_t size_)
     if (nbytes == 0)
         return -1; 
 
-    return (size_t) nbytes;
+    return nbytes;
 
 #else