Include the timeout value here like we do elsewhere

Closes #176

Author: bjori

src/mongoc/mongoc-buffer.c

@@ -177,8 +177,8 @@ _mongoc_buffer_append_from_stream (mongoc_buffer_t *buffer,
       bson_set_error (error,
                       MONGOC_ERROR_STREAM,
                       MONGOC_ERROR_STREAM_SOCKET,
-                      "Failed to read %"PRIu64" bytes from socket.",
-                      (uint64_t)size);
+                      "Failed to read %"PRIu64" bytes from socket within %d milliseconds.",
+                      (uint64_t)size, (int)timeout_msec);
       RETURN (false);
    }