MDEV-26879: Detach innodb_evict_tables_on_commit_debug from SAFE_MUTEX

In commit 18535a40 (MDEV-24811)
the implementation of innodb_evict_tables_on_commit_debug
depended on dict_sys.mutex and SAFE_MUTEX.
That is no longer the case.

SAFE_MUTEX is not available on Microsoft Windows.

storage/innobase/handler/ha_innodb.cc

@@ -200,7 +200,7 @@ static char*	innodb_version_str = (char*) INNODB_VERSION_STR;
 extern uint srv_fil_crypt_rotate_key_age;
 extern uint srv_n_fil_crypt_iops;
 
-#if defined SAFE_MUTEX && defined UNIV_DEBUG
+#ifdef UNIV_DEBUG
 my_bool innodb_evict_tables_on_commit_debug;
 #endif
 
@@ -19615,12 +19615,10 @@ static MYSQL_SYSVAR_BOOL(trx_purge_view_update_only_debug,
   " but the each purges were not done yet.",
   NULL, NULL, FALSE);
 
-# ifdef SAFE_MUTEX
 static MYSQL_SYSVAR_BOOL(evict_tables_on_commit_debug,
   innodb_evict_tables_on_commit_debug, PLUGIN_VAR_OPCMDARG,
   "On transaction commit, try to evict tables from the data dictionary cache.",
   NULL, NULL, FALSE);
-# endif /* SAFE_MUTEX */
 
 static MYSQL_SYSVAR_UINT(data_file_size_debug,
   srv_sys_space_size_debug,
@@ -19895,9 +19893,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
   MYSQL_SYSVAR(trx_rseg_n_slots_debug),
   MYSQL_SYSVAR(limit_optimistic_insert_debug),
   MYSQL_SYSVAR(trx_purge_view_update_only_debug),
-# ifdef SAFE_MUTEX
   MYSQL_SYSVAR(evict_tables_on_commit_debug),
-# endif /* SAFE_MUTEX */
   MYSQL_SYSVAR(data_file_size_debug),
   MYSQL_SYSVAR(fil_make_page_dirty_debug),
   MYSQL_SYSVAR(saved_page_number_debug),

storage/innobase/lock/lock0lock.cc

@@ -3873,7 +3873,7 @@ TRANSACTIONAL_TARGET static bool lock_release_try(trx_t *trx)
 and release possible other transactions waiting because of these locks. */
 void lock_release(trx_t *trx)
 {
-#if defined SAFE_MUTEX && defined UNIV_DEBUG
+#ifdef UNIV_DEBUG
   std::set<table_id_t> to_evict;
   if (innodb_evict_tables_on_commit_debug &&
       !trx->is_recovered && !trx->dict_operation &&
@@ -3937,7 +3937,7 @@ void lock_release(trx_t *trx)
   trx->lock.was_chosen_as_deadlock_victim= false;
   trx->lock.n_rec_locks= 0;
 
-#if defined SAFE_MUTEX && defined UNIV_DEBUG
+#ifdef UNIV_DEBUG
   if (to_evict.empty())
     return;
   dict_sys.lock(SRW_LOCK_CALL);