Problem:
When creating a temporary field for a temporary table in create_tmp_field_from_field(), a resulting field is created as an exact copy of an original one (in Field::new_field()). However, Field_enum and Field_set contain a pointer (typelib) to memory allocated in the parent table's MEM_ROOT, which under some circumstances may be deallocated later by the time a temporary table is used.
Solution:
Override the new_field() method for Field_enum and Field_set and create a separate copy of the typelib structure in there.
(Mostly in DBUG_PRINT() and unused arguments)
Fixed bug in query cache when used with traceing (--with-debug)
Fixed memory leak in mysqldump
Removed warnings from mysqltest scripts (replaced -- with #)
New multi-key-cache handling. This was needed becasue the old one didn't work reliable with MERGE tables.
ALTER TABLE table_name ... CHARACTER SET ... now changes all char/varchar/text columns to the given character set
(One must use ALTER TABLE ... DEFAULT CHARACTER SET ... to change the default character set)
Fixed that have_compress is detected properly (fixes problems with func_compress.test on platforms without zlib)
New syntax for CACHE INDEX ('keys' is optional if no index name is given and one mentions the key cache name only ones)
Removed compiler warnings
Added mysql_set_server_option() to allow clients like PHP to easaily set/reset the multi-statement flag.
