fix up test cases.


mysql-test/r/information_schema.result:
  update result for INFORMATION_SCHEMA.FILES
mysql-test/r/information_schema_db.result:
  update result for INFORMATION_SCHEMA.FILES
sql/ha_ndbcluster.cc:
  in fill_files_table, use my_snprintf instead of snprintf
sql/sql_show.cc:
  correct DBUG_ENTER for fill_schema_files
sql/table.h:
  add SCH_FILES to information schema enum