The return values were getting dangerously close to the range of meaningful
values, in particular the next candidate 63 is equal to '?' which is the
typical return value in case of error.

The return values for long options may be any integer, so bump them up to
outside the ascii range, start above 1000. For ease of review this patch, keep
the existing range (41-62) and increment each value by 1000.

Tested:
- Ran "criu --help", works fine.
- Manual dump and restore with some of the options, worked fine.
- Ran the zdtm test suite, tests passed.
Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>