in older version.

The problem is that TRN-files created in "old" versions contain
junk in trigger_table field, which is not acceptable in "new" versions.


sql/parse_file.cc:
  1. Made parse_escaped_string() available globally;
  2. Polishing: fixing the comments.
sql/parse_file.h:
  Made parse_escaped_string() available globally.
sql/sql_trigger.cc:
  1. Polishing
  2. Removed declaration of global handle_old_incorrect_sql_modes()
     since it is not used anymore.
  3. Added a hook to support invalid "trigger_table" field in TRN-file
     from old versions.