These functions are not used with ext/re.
Variables possibly clobbered by longjmp/vfork.

(my_perl in the line 480 has the same problem, but messier to fix.)
If no lchown, not using the args.
g++ groks __attribute__((unused)) at least since 4.3.6.

Cannot find the exact moment from gcc release notes, but tests fine in 4.3.6.
(not fine = "warning: unused ...")