revision: use die_for_incompatible_opt3() for - -graph/--reverse/--walk-reflogs
The revision option --reverse is incompatible with --walk-reflogs and
--graph is incompatible with both --reverse and --walk-reflogs. So they
are all incompatible with each other.
Use the function for checking three mutually incompatible options,
die_for_incompatible_opt3(), to perform this check in one place and
without repetition. This is shorter and clearer.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>