rev-parse: put all options under the "-" check

rev-parse: put all options under the "-" check

The option-parsing loop of rev-parse checks whether the first character
of an arg is "-". If so, then it enters a series of conditionals
checking for individual options. But some options are inexplicably
outside of that outer conditional.

This doesn't produce the wrong behavior; the conditional is actually
redundant with the individual option checks, and it's really only its
fallback "continue" that we care about. But we should at least be
consistent.

One obvious alternative is that we could get rid of the conditional
entirely. But we'll be using the extra block it provides in the next
patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>