seq: New module for race-free, pollable, thread-safe sequence number.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>

lib/poll-loop.c

@@ -26,6 +26,7 @@
 #include "fatal-signal.h"
 #include "list.h"
 #include "ovs-thread.h"
+#include "seq.h"
 #include "socket-util.h"
 #include "timeval.h"
 #include "vlog.h"
@@ -248,6 +249,8 @@ poll_block(void)
 
     /* Handle any pending signals before doing anything else. */
     fatal_signal_run();
+
+    seq_woke();
 }
 
 static void