added get_field_default_value() function which obtains default value from the field
(used in store_create_info() & get_schema_column_record() functions)


mysql-test/r/alter_table.result:
  result fix
mysql-test/r/create.result:
  result fix
mysql-test/r/ctype_collate.result:
  result fix
mysql-test/r/ctype_recoding.result:
  result fix
mysql-test/r/default.result:
  result fix
mysql-test/r/gis.result:
  result fix
mysql-test/r/grant.result:
  result fix
mysql-test/r/information_schema.result:
  result fix
mysql-test/r/key.result:
  result fix
mysql-test/r/mysql.result:
  result fix
mysql-test/r/ps_1general.result:
  result fix
mysql-test/r/show_check.result:
  result fix
mysql-test/r/sp.result:
  result fix
mysql-test/r/type_enum.result:
  result fix
mysql-test/r/type_ranges.result:
  result fix
mysql-test/t/information_schema.test:
  test case