single-table UPDATE/DELETE.


mysql-test/r/partition_pruning.result:
  WL#2985 "Partition pruning": addition2: perform partition pruning for UPDATE/DELETE:
  testcases added
mysql-test/t/partition_pruning.test:
  WL#2985 "Partition pruning": addition2: perform partition pruning for UPDATE/DELETE:
  testcases added
sql/sql_delete.cc:
  WL#2985 "Partition pruning": addition2: perform partition pruning for UPDATE/DELETE:
  Added partition pruning call in mysql_delete()
sql/sql_update.cc:
  WL#2985 "Partition pruning": addition2: perform partition pruning for UPDATE/DELETE:
  Added partition pruning call in mysql_update()