[Bug c/67957] gcc's printf attribute accepts %m as a format character

[christos at zoulas dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67957

--- Comment #1 from Christos Zoulas <christos at zoulas dot com> ---
Created attachment 36504
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36504&action=edit
patch