Add removal safe TAILQ iterator.

TAILQ_FOREACH macro was not safe for element removal as it was
accessing the next element in case of a free. This patch is inspired
by Linux list handling and provide a new macro TAILQ_FOREACH_SAFE.
This macro is removal safe and only differs by a last argument being
a temporaty pointer to an element.

src/queue.h

@@ -346,6 +346,13 @@ struct {								\
 	    (var) != TAILQ_END(head);					\
 	    (var) = TAILQ_NEXT(var, field))
 
+/* removal safe iterator using a temprary element has last param */
+#define TAILQ_FOREACH_SAFE(var, head, field, tvar)					\
+	for((var) = TAILQ_FIRST(head), \
+        (tvar) = TAILQ_FIRST(head) ? TAILQ_NEXT(TAILQ_FIRST(head), field): NULL ; \
+	    (var) != TAILQ_END(head);					\
+	    (var = tvar), (tvar) = var ? TAILQ_NEXT(var, field): NULL)
+
 #define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
 	for((var) = TAILQ_LAST(head, headname);				\
 	    (var) != TAILQ_END(head);					\

src/unix-manager.c

@@ -748,7 +748,8 @@ void *UnixManagerThread(void *td)
 
         if ((ret == 0) || (TmThreadsCheckFlag(th_v, THV_KILL))) {
             UnixClient *item;
-            TAILQ_FOREACH(item, &(&command)->clients, next) {
+            UnixClient *titem;
+            TAILQ_FOREACH_SAFE(item, &(&command)->clients, next, titem) {
                 close(item->fd);
                 SCFree(item);
             }