Old FRM files didn't allow byte 255 as a column name part.
Since now we store column names in UTF8, this restriction
is not required anymore: 255 is not a valid byte in UTF8.
Fix: removing checking against 255.


mysql-test/r/ctype_latin1.result:
  Adding test case
mysql-test/t/ctype_latin1.test:
  Adding test case
sql/sql_lex.cc:
  Removing old code, unnecessary anymore.