sql_yacc.yy:
  WL3527: updated the diff to use correct parser words
table.cc:
  WL3527: exteneded the fix for bug #20604 to fit the new variables
sql_select.cc:
  WL3527: renamed used_keys to covering_keys


sql/sql_select.cc:
  renamed used_keys to covering_keys
sql/sql_yacc.yy:
  WL3527: updated the diff to use correct parser words
sql/table.cc:
  WL3527: exteneded the fix for bug #20604 to fit the new variables