MDEV-31558 Add InnoDB engine information to the slow query log

The new statistics is enabled by adding the "engine", "innodb" or "full"
option to --log-slow-verbosity

Example output:

 # Pages_accessed: 184  Pages_read: 95  Pages_updated: 0  Old_rows_read: 1
 # Pages_read_time: 17.0204  Engine_time: 248.1297

Page_read_time is time doing physical reads inside a storage engine.
(Writes cannot be tracked as these are usually done in the background).
Engine_time is the time spent inside the storage engine for the full
duration of the read/write/update calls. It uses the same code as
'analyze statement' for calculating the time spent.

The engine statistics is done with a generic interface that should be
easy for any engine to use. It can also easily be extended to provide
even more statistics.

Currently only InnoDB has counters for Pages_% and Undo_% status.
Engine_time works for all engines.

Implementation details:

class ha_handler_stats holds all engine stats.  This class is included
in handler and THD classes.
While a query is running, all statistics is updated in the handler. In
close_thread_tables() the statistics is added to the THD.

handler::handler_stats is a pointer to where statistics should be
collected. This is set to point to handler::active_handler_stats if
stats are requested. If not, it is set to 0.
handler_stats has also an element, 'active' that is 1 if stats are
requested. This is to allow engines to avoid doing any 'if's while
updating the statistics.

Cloned or partition tables have the pointer set to the base table if
status are requested.

There is a small performance impact when using --log-slow-verbosity=engine:
- All engine calls in 'select' will be timed.
- IO calls for InnoDB reads will be timed.
- Incrementation of counters are done on local variables and accesses
  are inline, so these should have very little impact.
- Statistics has to be reset for each statement for the THD and each
  used handler. This is only 40 bytes, which should be neglectable.
- For partition tables we have to loop over all partitions to update
  the handler_status as part of table_init(). Can be optimized in the
  future to only do this is log-slow-verbosity changes. For this to work
  we have to update handler_status for all opened partitions and
  also for all partitions opened in the future.

Other things:
- Added options 'engine' and 'full' to log-slow-verbosity.
- Some of the new files in the test suite comes from Percona server, which
  has similar status information.
- buf_page_optimistic_get(): Do not increment any counter, since we are
  only validating a pointer, not performing any buf_pool.page_hash lookup.
- Added THD argument to save_explain_data_intern().
- Switched arguments for save_explain_.*_data() to have
  always THD first (generates better code as other functions also have THD
  first).

sql/sql_class.h

@@ -51,6 +51,7 @@
 #include "backup.h"
 #include "xa.h"
 #include "ddl_log.h"                            /* DDL_LOG_STATE */
+#include "ha_handler_stats.h"                    // ha_handler_stats */
 
 extern "C"
 void set_thd_stage_info(void *thd,
@@ -1870,6 +1871,7 @@ public:
   ulonglong cuted_fields, sent_row_count, examined_row_count;
   ulonglong affected_rows;
   ulonglong bytes_sent_old;
+  ha_handler_stats handler_stats;
   ulong     tmp_tables_used;
   ulong     tmp_tables_disk_used;
   ulong     query_plan_fsort_passes;
@@ -2707,6 +2709,7 @@ public:
   struct  system_status_var status_var; // Per thread statistic vars
   struct  system_status_var org_status_var; // For user statistics
   struct  system_status_var *initial_status_var; /* used by show status */
+  ha_handler_stats handler_stats;       // Handler statistics
   THR_LOCK_INFO lock_info;              // Locking info of this thread
   /**
     Protects THD data accessed from other threads: