mkfs: support arbitrary conflict specification

mkfs: support arbitrary conflict specification

Currently the conflict table is a single dimension, allowing
conflicts to be specified in the same option table. however, we
have conflicts that span option tables (e.g. sector size) and
so we need to encode both the table and the option that conflicts.

Add support for a two dimensional conflict definition and convert
all the code over to use it.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>