- Detect if a table has field of type MYSQL_TYPE_VAR_STRING while running
   "CHECK TABLE t FOR UPGRADE" and indicate it need to be fixed
   with "REPAIR TABLE t".
 - When running a "REPAIR TABLE t" or "ALTER TABLE t FORCE" on the above
   table, install a special copy function to trim off the trailing spaces
   which we safely can say that the pre 5.0 mysqld didn't put there. 


mysql-test/r/varbinary.result:
  Add test to see that a table with varbinary from 4.1 can be REPAIRED
mysql-test/t/varbinary.test:
  Add test to see that a table with varbinary from 4.1 can be REPAIRED
sql/field_conv.cc:
  Add new field copy function 'do_field_varbinary_pre50' used for copying
  between MYSQL_TYPE_VAR_STRING and MYSQL_TYPE_VARCHAR. It will remove trailing
  spaces from the field as MySQL <= 4.1 never stores the trailing spaces for
  a MYSQL_TYPE_VAR_STRING.
  Install this new copy function in ALTER TABLEs list of functions to use for
  copying data during and alter if from field is a <= 4.1 varbinary and to
  field is 5.0 varbinary.
sql/handler.cc:
  If the table has a pre 5.0 varbinary, table not to be altered so the field
  type is upgraded to 5.0 version and trailing space can be trimmed.
mysql-test/std_data/bug19371.MYD:
  New BitKeeper file ``mysql-test/std_data/bug19371.MYD''
mysql-test/std_data/bug19371.MYI:
  New BitKeeper file ``mysql-test/std_data/bug19371.MYI''
mysql-test/std_data/bug19371.frm:
  New BitKeeper file ``mysql-test/std_data/bug19371.frm''