SELECT queries on information_schema table will now not store data
in the temporary table for columns that are not used in the query.
This can drastically reduce memory when there are many rows involved
in a query, like using
SELECT table_name FROM information_schema.table
on a system with many tables.
The difference for the above query is about 14K per existing table.

The code works this way:
- Create a bitmap for all information_schema fields used in the query
- For BLOB and VARCHAR fields that are not use, create a Field_null field.

Remove compiler warnings in sphinx, item_sum.cc and opt_split.cc

This is needed as otherwise a lot of MyISAM tables may be marked
as crashed, depending on in which order tests are run

Renamed suite/rpl/include/rpl_sync.inc to rpl_sync_test.inc to
remove clash with include/rpl_sync.inc

This is done to get more free flag bits for alter_info->flags

Renamed all ALTER PARTITION defines to start with ALTER_PARTITION_
Renamed ALTER_PARTITION to ALTER_PARTITION_INFO
Renamed ALTER_TABLE_REORG to ALTER_PARTITION_TABLE_REORG

Other things:
- Shifted some ALTER_xxx defines to get empty bits at end

Main reason was to make it easier to print the above structures in
a debugger. Additional benefits is that I was able to use same
defines for both structures, which simplifes some code.

Most of the code is just removing Alter_info:: and Alter_inplace_info::
from alter table flags.

Following renames was done:
HA_ALTER_FLAGS        -> alter_table_operations
CHANGE_CREATE_OPTION  -> ALTER_CHANGE_CREATE_OPTION
Alter_info::ADD_INDEX -> ALTER_ADD_INDEX
DROP_INDEX            -> ALTER_DROP_INDEX
ADD_UNIQUE_INDEX      -> ALTER_ADD_UNIQUE_INDEX
DROP_UNIQUE_INDEx     -> ALTER_DROP_UNIQUE_INDEX
ADD_PK_INDEX          -> ALTER_ADD_PK_INDEX
DROP_PK_INDEX         -> ALTER_DROP_PK_INDEX
Alter_info:ALTER_ADD_COLUMN    -> ALTER_PARSE_ADD_COLUMN
Alter_info:ALTER_DROP_COLUMN   -> ALTER_PARSE_DROP_COLUMN
Alter_inplace_info::ADD_INDEX  -> ALTER_ADD_NON_UNIQUE_NON_PRIM_INDEX
Alter_inplace_info::DROP_INDEX -> ALTER_DROP_NON_UNIQUE_NON_PRIM_INDEX

Other things:
- Added typedef alter_table_operatons for alter table flags
- DROP CHECK CONSTRAINT can now be done online
- Added checks for Aria tables in alter_table_online.test
- alter_table_flags now takes an ulonglong as argument.
- Don't support online operations if checksum option is used.
- sql_lex.cc doesn't add ALTER_ADD_INDEX if index is not created

fill_alter_table() always thought that index was changed because of
of a wrong check of block_size. Some engines had code to correct this
that should not be needed, Aria didn't and because of this some online
operations didn't work.

This code fixes the comparision of block_size to only compare if it's set.

Currently trx_sys.mutex protects only trx_sys.mysql_trx_list and
trx_sys.m_views, which are not accessed by lock0lock debug routines.
Thus there's no need to bother trx_sys.mutex here.

Removed trx_assert_started(): this assertion is fully covered by
check_trx_state().

recv_sys_t::mutex and rw_trx_hash_elementi_t::mutex were acquired
in reverse (to recorded) order.

Fixed by releasing recv_sys_t::mutex, before iterating rw_trx_hash.
Statistics gathering doesn't really need recv_sys_t::mutex protection,
since it is always done in one thread (trx_roll_crash_recv_trx) and
thus it can't go wrong.

This is fixup after commit 8026cd62.
We must not silently allow a lock wait to occur during InnoDB data
dictionary transactions. The dict_operation_lock is supposed to
prevent lock waits, and we want to be aware of any errors.

Implementing the task according to the description.
Additionally, implementing Item_func_date_format::check_arguments().

Main changes:

- Changing the constructor to accept a CHARSET_INFO pointer, instead of an Item pointer
- Updating the bison grammar accordingly

Additional cleanups:

- Simplifying Item_func_set_collation::eq() by reusing Item_func::eq()
- Removing unused binary_keyword

Problem:
=======
	During validation of missing tablespace, missing tablespace id is
being compared with hash table of redo logs (recv_sys->addr_hash). But if the
hash table ran out of memory then there is a possibility that it will not contain
the redo logs of all tablespace. In that case, Server will load the InnoDB
even though there is a missing tablespace.

Solution:
========
	If the recv_sys->addr_hash hash table ran out of memory then InnoDB needs
to scan the remaining redo log again to validate the missing tablespace.

The problem resided in this branch of the "option_value_no_option_type" rule:

| '@' '@' opt_var_ident_type internal_variable_name equal set_expr_or_default

Summary:

1. internal_variable_name initialized tmp.var to trg_new_row_fake_var (0x01).
2. The condition "if (tmp.var == NULL)" did not check
   the special case with trg_new_row_fake_var,
   so Lex->set_system_variable(&tmp, $3, $6) was
   called with tmp.var pointing to trg_new_row_fake_var,
   which created a sys_var instance pointing to 0x01 instead of
   a real system variable.
3. Later, at the trigger invocation time, this method was called:
   sys_var::do_deprecated_warning (this=0x1, thd=0x7ffe6c000a98)
   Notice, "this" is equal to trg_new_row_fake_var (0x01)

Solution:

The old implementation with separate rules
internal_variable_name (in sql_yacc.yy and sql_yacc_ora.yy) and
internal_variable_name_directly_assignable (in sql_yacc_ora.yy only)
was too complex and hard to follow.

Rewriting the code in a more straightforward way.

1. Changing LEX::set_system_variable()

from:

bool set_system_variable(struct sys_var_with_base *, enum_var_type, Item *);

to:

bool set_system_variable(enum_var_type, sys_var *, const LEX_CSTRING *, Item *);

2. Adding new methods in LEX, which operate with variable names:

bool set_trigger_field(const LEX_CSTRING *, const LEX_CSTRING *, Item *);
bool set_system_variable(enum_var_type var_type, const LEX_CSTRING *name,
                         Item *val);
bool set_system_variable(THD *thd, enum_var_type var_type,
                         const LEX_CSTRING *name1,
                         const LEX_CSTRING *name2,
                         Item *val);
bool set_default_system_variable(enum_var_type var_type,
                                 const LEX_CSTRING *name,
                                 Item *val);
bool set_variable(const LEX_CSTRING *name, Item *item);

3. Changing the grammar to call the new methods directly
   in option_value_no_option_type,
   Removing rules internal_variable_name and
   internal_variable_name_directly_assignable.

4. Removing "struct sys_var_with_base" and trg_new_row_fake_var.

Good side effect:

- The code in /sql reduced from 314 to 183 lines.
- MDEV-15615 Unexpected syntax error instead of "Unknown system variable" ...
  was also fixed automatically

When the plugin is unloaded, walk the s_trx_list and delete the left over
Rdb_transaction objects.
It is responsibility of the SQL layer to make sure that the storage engine
has no open tables when the plugin is being unloaded.

Scientific notation handling fixed.

Conflicts:
	mysql-test/r/func_json.result
	mysql-test/t/func_json.test

Scientific notation handling fixed.

and remove redundant have_innodb.inc, it's included in
galera_cluster.inc anyway.

and remove redundant have_innodb.inc, it's included in
galera_cluster.inc anyway.

extra/mariabackup/ds_buffer.c:145:9: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]

information can be obtained.

plugin only enabled for Linux, as it fails building on BSD/MacOSX.
disks.test fixed.

information can be obtained.

disks.test moved to plugin's directory.