crush: fix fast rule lookup when uniform

crush: fix fast rule lookup when uniform

Older clients will search for the first rule with a matching ruleset,
type, and size.  The has_uniform_rules bool is only set if we have rule
ids and rulesets that line up, but we must also verify that the rest of the
mask matches or else we can get a different CRUSH mapping result because
the mask might not match and old clients will fail to find a rule and we
will find one.  We also can't just check the ruleset as the legacy clients
find the *first* (of potentially many) matching rules; hence we only do
the fast check if all rulesets == rule id.

Signed-off-by: Sage Weil <sage@redhat.com>