If no strtoul, the args are unused.

(strtoul is defined as not_here() if not found.)
The format is not a literal but well defined.
Possibly uninitialized.

op.c:8346:21: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
op.c:8811:21: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
stdize_locale not used in POSIX.
Label conditionally unused.