Merge branch 'maint'

* maint:
  compat: helper for detecting unsigned overflow

wrapper.c

@@ -53,7 +53,7 @@ void *xmalloc(size_t size)
 void *xmallocz(size_t size)
 {
 	void *ret;
-	if (size + 1 < size)
+	if (unsigned_add_overflows(size, 1))
 		die("Data too large to fit into virtual memory space.");
 	ret = xmalloc(size + 1);
 	((char*)ret)[size] = 0;