Fixed small error in new .FRM parser which caused it to handle 
improperly escaped strings.


mysql-test/r/trigger.result:
  Added test for bug #5887 "Triggers with string literals cause errors".
mysql-test/t/trigger.test:
  Added test for bug #5887 "Triggers with string literals cause errors".
sql/parse_file.cc:
  read_escaped_string(): We should not fail when we meet \' sequence 
  in escaped string.