Fix tests for libxml2 > 2.8
Fix tests for libxml2 > 2.8

be9/redcarpet,gitcafe-dev/redcarpet,kaneshin/redcarpet,gitcafe-dev/redcarpet,gitcafe-dev/redcarpet,Hacker0x01/redcarpet,Hacker0x01/redcarpet,emq/redcarpet,fukayatsu/redcarpet,increments/greenmat,emq/redcarpet,kattybilly/redcarpet,JuanitoFatas/redcarpet,be9/redcarpet,increments/greenmat,kaneshin/redcarpet,be9/redcarpet,JuanitoFatas/redcarpet,fukayatsu/redcarpet,liquorburn/redcarpet,fukayatsu/redcarpet,vmg/redcarpet,increments/greenmat,kaneshin/redcarpet,emq/redcarpet,JuanitoFatas/redcarpet,increments/greenmat,kaneshin/redcarpet,vmg/redcarpet,kattybilly/redcarpet,kattybilly/redcarpet,kattybilly/redcarpet,be9/redcarpet,fukayatsu/redcarpet,vmg/redcarpet,vmg/redcarpet,liquorburn/redcarpet,liquorburn/redcarpet,liquorburn/redcarpet,Hacker0x01/redcarpet,Hacker0x01/redcarpet,emq/redcarpet