- IF EXISTS ends with a list of all not existing object, instead of a
  separate note for every not existing object
- Produce a "Note" for all wrongly dropped objects
  (like trying to do DROP SEQUENCE for a normal table)
- Do not write existing tables that could not be dropped to binlog

Other things:
MDEV-22820 Bogus "Unknown table" warnings produced upon attempt to drop
           parent table referenced by FK
This was caused by an older version of this commit patch and later fixed