intended, the format string parser that generates the va_list does not support
all formatting characters.
Make this code portable by failing to parse any format string at all, not just
the ones that aren't fully supported.
Bump PKGREVISION for the functional change, though this code is probably
generally unused anyway. Unmark as BROKEN and NOT_FOR_PLATFORM - I think all
uses of va_list casts are inhibited.
67f995f0ab