revision: fix --left/right-only use with unrelated histories

revision: fix --left/right-only use with unrelated histories

This is a similar fix as 023756f4eb (revision walker: --cherry-pick is a
limited operation), but for the --left-only and --right-only options.

When computing a symmetric difference between two unrelated histories,
no suitable merge base exists, and so no boundary commit is flagged as
UNINTERESTING.  Previously, we relied on the presence of such boundary
to trigger limiting and thus consideration of either "revs->left_only"
or "revs->right_only".

A number of other entries in the option parser have started including
overrides for "revs->limited = 1".  Do the same for these options.

Signed-off-by: Matt Hunter <m@lfurio.us>
Signed-off-by: Junio C Hamano <gitster@pobox.com>