[Bug c/58959] Add warning when format specifiers refers to wrong signess

[lotharlutz at gmx dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58959

--- Comment #1 from Markus Mayer <lotharlutz at gmx dot de> ---
Created attachment 31131
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31131&action=edit
preprocessed test file