The attached patch adds a method
handlerton::fill_is_table that can be used
instead of having to create specific
handlerton::fill_*_table methods.

sql/ha_ndbcluster.cc:
  WL#4448 Generalize the handlerton::fill_files_table call with handlerton::fill_is_table
  
  Implemented the method ndbcluster_fill_is_table
  that uses the supplied table id to switch to the
  appropriate fill_*_table method.
sql/handler.h:
  WL#4448 Generalize the handlerton::fill_files_table call with handlerton::fill_is_table
  
  Moved the enum_schema_table enumeration
  from table.h to here. 
  
  contains the declaration for the new method
  fill_is_tables.
sql/sql_show.cc:
  WL#4448 Generalize the handlerton::fill_files_table call with handlerton::fill_is_table
  
  calls the fill_is_table method instead of the
  fill_files_table method.
sql/table.h:
  WL#4448 Generalize the handlerton::fill_files_table call with handlerton::fill_is_table
  
  removed the earlier definition of enum_schema_tables.