TTF library causes core dump on Irix

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=1527

Reported by Fredrik Noring, Roxen Internet Software noring@roxen.com

Pike 7.0 compiled by cc on Irix makes the TTF library dump core:

  $ make run_hilfe
  Pike v7.0 release 330 running Hilfe v2.0 (Incremental Pike Frontend)
  > indices(_Image_TTF);
  make: *** [run_hilfe] Segmentation fault (core dumped)

(gcc doesn't work either, see [bug #1145 (closed)].)