memleak: restore functionality accidentally removed.

Accidentally removed in 6c9b752751.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/memleak.c

@@ -106,6 +106,7 @@ static void children_into_htable(const void *exclude1, const void *exclude2,
 			if (streq(name, "tmpctx"))
 				continue;
 		}
+		htable_add(memtable, hash_ptr(i, NULL), i);
 		children_into_htable(exclude1, exclude2, memtable, i);
 	}
 }