parse the ignore flag before all others
parse the ignore flag before all others

The legacy implementation doesn't support "%+_", "%-_" etc. which were
accepted by Benoît's patches. This creates a discrepancy (though not
a regression) that is not necessarily desirable (and in any case makes
fuzz-testing for difference return non-bugs). Long-term, I think that
we're good with the previous, simpler structure where "_" must always
be the first flag.

git-svn-id: e7e61699ce1738538ffebb75374fbea0924bc775@14827 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

gerdstolpmann/ocaml,msprotz/ocaml,msprotz/ocaml,eliberis/ocaml,eliberis/ocaml,yunxing/ocaml,yunxing/ocaml,yunxing/ocaml,yunxing/ocaml,gerdstolpmann/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,eliberis/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,msprotz/ocaml