Implement flow control

This commit introduces the necessary changes necessary
for implementing flow control. None of the socket types
implements the flow control yet. The code will crash when
the flow control is enabled and the thw lwm is reached.

The following commits will add flow-control support for
individual socket types.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/err.hpp b/src/err.hpp
index 6c13b02..2b76569 100644
--- a/src/err.hpp
+++ b/src/err.hpp
@@ -115,3 +115,9 @@ namespace zmq
     } while (false)
 
 #endif
+
+#define zmq_not_implemented() \
+    do {\
+        fprintf (stderr, "Hic sunt leones (%s:%d)\n", __FILE__, __LINE__);\
+        abort ();\
+    } while (false)