MDEV-32899 instrumentation

In debug builds, let us declare dict_sys.latch as index_lock instead of
srw_lock, so that we will benefit from the full tracking of lock ownership.

lock_table_for_trx(): Assert that the current thread is not holding
dict_sys.latch. If the dict_sys.unfreeze() call were moved to the end of
lock_table_children(), this assertion would fail in the test innodb.innodb
and many other tests that use FOREIGN KEY.

mysql-test/suite/perfschema/r/sxlock_func,debug.rdiff

@@ -0,0 +1,22 @@
+@@ -7,7 +7,6 @@
+ WHERE name LIKE 'wait/synch/rwlock/innodb/%'
+ AND name!='wait/synch/rwlock/innodb/btr_search_latch' ORDER BY name;
+ name
+-wait/synch/rwlock/innodb/dict_operation_lock
+ wait/synch/rwlock/innodb/fil_space_latch
+ wait/synch/rwlock/innodb/lock_latch
+ wait/synch/rwlock/innodb/trx_i_s_cache_lock
+@@ -19,11 +18,13 @@
+ select name from performance_schema.setup_instruments
+ where name like "wait/synch/sxlock/%" order by name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ SELECT DISTINCT name FROM performance_schema.rwlock_instances
+ WHERE name LIKE 'wait/synch/sxlock/innodb/%'
+ ORDER BY name;
+ name
++wait/synch/sxlock/innodb/dict_operation_lock
+ wait/synch/sxlock/innodb/index_tree_rw_lock
+ create table t1(a int) engine=innodb;
+ begin;

mysql-test/suite/perfschema/t/sxlock_func.test

@@ -5,6 +5,7 @@
 --source include/not_embedded.inc
 --source include/have_perfschema.inc
 --source include/have_innodb.inc
+--source include/maybe_debug.inc
 
 UPDATE performance_schema.setup_instruments SET enabled = 'NO', timed = 'YES';