Use tor_malloc_zero(x), not tor_calloc(x,sizeof(char))

(Also, fixes a wide line.)

src/common/util.c

@@ -3465,8 +3465,9 @@ format_win_cmdline_argument(const char *arg)
     smartlist_add(arg_chars, (void*)&backslash);
 
   /* Allocate space for argument, quotes (if needed), and terminator */
-  formatted_arg = tor_calloc((smartlist_len(arg_chars) + (need_quotes ? 2 : 0) + 1),
-                             sizeof(char));
+  const size_t formatted_arg_len = smartlist_len(arg_chars) +
+    (need_quotes ? 2 : 0) + 1;
+  formatted_arg = tor_malloc_zero(formatted_arg_len);
 
   /* Add leading quote */
   i=0;