Fix: crmd: Do not update fail-count and last-failure for old failures

A DC election may introduce a lrm status refresh. If there are
previously failed lrm operations, crmd will notice them as "Old event".
While that will still trigger the update of fail-count and last-failure.
If the resource has "migration-threshold" or "failure-timeout"
attribute, that can cause unnecessary migration.
Merge pull request #274 from gao-yan/old-failure

Fix: crmd: Do not update fail-count and last-failure for old failures