Backport the column prefix memory corruption fix from 5.0

  Manually merge the latest FOREIGN KEY lock wait + DROP TABLE fix from 4.0

  Fix the previous bug fix: dropping a table with FOREIGN KEY checks running on it caused a cascade of failed drops while the foreign key check was waiting for a lock

  Merge the two FOREIGN KEY bug fixes from 4.0, and add a TODO comment

  Fix bug: if we dropped a table where an INSERT was waiting for a lock to check a FOREIGN KEY constraint, then an assertion would fail in lock_reset_all_on_table(), since that operation assumes no waiting locks on the table or its records
row0mysql.c:
  Fix bug: InnoDB failed to drop a table in the background drop queue if the table was referenced by a foreign key constraint

  Fix typo

  Fix InnoDB critical bug #7496; we scan the InnoDB data dictionary also at a normal mysqld startup, and create the spaces, so that we know the mapping space id -> .ibd file name; fix an infinite loop if DISCARD TABLESPACE coincides with INSERT or some other table operation; fix a potential crash if DISCARD TABLESPACE coincides with a cascaded FOREIGN KEY operation in the same table; do not allow DISCARD TABLESPACE of a referenced table if FOREIGN_KEY_CHECKS=1

  Fix bug #6817 and bug #6827 : do not crash the server if the buffer pool becomes filled by the locks of ONE huge transaction, return error 1206 instead; do not crash the server, but return error if we cannot allocate memory for the buffer pool at a mysqld startup

  Fix bug #3478: InnoDB's FOREIGN KEY tables treated table and database names as case-insensitive; RENAME TABLE t to T would hang in an endless loop if t had a foreign key constraint defined on it
dict0dict.c:
  Fix bug #3478: InnoDB's FOREIGN KEY tables treated table and database names as case-insensitive; RENAME TABLE t to T would hang in an endless loop if t had a foreign key constraint defined on it; fix also a hang that would occur if one tried in ALTER TABLE or RENAME TABLE to create a foreign key constraint name that collided with another existing name

  Print more warnings to the .err log if ALTER TABLE ... IMPORT TABLESPACE fails for some reason
os0file.c:
  Do not call exit(1) if os_file_delete() fails; remove unused parameter from
handle_error_no_exit()

fil0fil.c:
  Allow DROP TABLE even if the .ibd file for the table does not exist

  Fix bug #5961: release the dictionary latch during a long cascaded FOREIGN KEY operation, so that we do not starve other users

  If one tries to drop an InnoDB table without an .ibd file, print to .err log that we DID remove the table from the internal data dictionary of InnoDB, and return DB_SUCCESS so that MySQL will delete the .frm file; the drawback in this is that then DROP TABLE returns success, and the user is not alerted; maybe it could return a warning

  Fix bug #5137: if innodb_file_per_table was specified, CREATE TEMPORARY TABLE ... TYPE=InnoDB said that cannot find path specified, and made mysqld to exit(1)

  Raise maximum column prefix len to 767 bytes, so that MySQL can create a column prefix index of 255 UTF-8 characters (each takes 3 bytes at the maximum); add comments about why innobase_get_at_most_n_mbchars() works ok
dict0mem.h:
  Raise maximum column prefix len to 767 bytes, so that MySQL can create a column prefix index of 255 UTF-8 characters (each takes 3 bytes at the maximum)
row0mysql.c:
  If MySQL tries to create a column prefix index longer that 255 UTF-8 characters, give an error, and drop the table from the InnoDB internal data dictionary. MySQL did not drop the table there in its own error handling.

  row_drop_table_for_mysql(): Removed duplicated block of code.

  Fix bug: if we RENAME a table, InnoDB forgot to load the foreign key constraints that reference the new table name, and forgot to check that they are compatible with the table

  row_drop_table_for_mysql(): Removed a ut_ad() assertion that failed
  when a DROP TABLE is executed in the background.

(Bug #2694)

  Inside LOCK TABLES, use either LOCK_S or LOCK_X in locking reads; an improvent over the previous patch

allow deletion of tablespaces whose names contain "'"

Disable log archiving code unless #ifdef UNIV_LOG_ARCHIVE
Remove (char*) casts of string constants; add const qualifiers
Remove some Hot Backup code unless #ifdef UNIV_HOTBACKUP

Changed 'SHOW FIELD STATUS' to use 'Engine' instead of 'Type'

instead of stdout or fixed-size memory buffers

when dropping database (Bug #3058)