Fix an embarrasing typo in the WM-Aware binary heap layout.

The effect of this is that the root object in the binheap could be
wrong and thus hold the expiry thread hostage, even though other objects
were ripe for expiry. 

This would show up as inflated obj/objcore/objhdr counts, but have no
other deleritous effects.

Detected, conclusively, by:	sky


git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@5195 d4fa192b-c00b-0410-8231-f00ffab90ce4

lib/libvarnish/binary_heap.c

@@ -57,6 +57,9 @@ SVNID("$Id$")
  */
 #define ROW_SHIFT		16
 
+
+#undef PARANOIA
+
 /* Private definitions -----------------------------------------------*/
 
 #define ROOT_IDX		1
@@ -127,8 +130,12 @@ child(const struct binheap *bh, unsigned u, unsigned *a, unsigned *b)
 	} else {
 		/* The rest is as usual, only inside the page */
 		*a = u + (u & bh->page_mask);
-		*b += 1;
+		*b = *a + 1;
 	}
+#ifdef PARANOIA
+	assert(parent(bh, *a) == u);
+	assert(parent(bh, *b) == u);
+#endif
 }
 
 
@@ -284,12 +291,29 @@ binheap_insert(struct binheap *bh, void *p)
 	(void)binheap_trickleup(bh, u);
 }
 
+
+#ifdef PARANOIA
+static void
+chk(const struct binheap *bh)
+{
+	unsigned u, v;
+
+	for (u = 2; u < bh->next; u++) {
+		v = parent(bh, u);
+		assert(!bh->cmp(bh->priv, A(bh, u), A(bh, v)));
+	}
+}
+#endif 
+
 void *
 binheap_root(const struct binheap *bh)
 {
 
 	assert(bh != NULL);
 	assert(bh->magic == BINHEAP_MAGIC);
+#ifdef PARANOIA
+	chk(bh);
+#endif
 	return (A(bh, ROOT_IDX));
 }