EC: Add logic for striped blocks in isSufficientlyReplicated

/**
   * Check if a block is replicated to at least the minimum replication.
   */
  public boolean isSufficientlyReplicated(BlockInfo b) {
    // Compare against the lesser of the minReplication and number of live DNs.
    final int liveReplicas = countNodes(b).liveReplicas();
    if (liveReplicas >= minReplication) {
      return true;
    }
    // getNumLiveDataNodes() is very expensive and we minimize its use by
    // comparing with minReplication first.
    return liveReplicas >= getDatanodeManager().getNumLiveDataNodes();
  }