MDEV-33464 Crash when innodb_max_undo_log_size is set to innodb_page_size*4294967296

purge_sys_t::truncating_tablespace(): Clamp the
innodb_max_undo_log_size to the maximum number of pages
before converting the result into a 32-bit unsigned integer.

This fixes up commit f8c88d90 (MDEV-33213).

In later major versions, we would use 32-bit unsigned integer here
due to commit ca501ffb
and the code would crash also on 64-bit processors.

Reviewed by: Debarun Banerjee

mysql-test/suite/innodb/r/undo_truncate.result

@@ -25,6 +25,7 @@ delete from t1;
 connection con2;
 delete from t2;
 connection con1;
+SET GLOBAL innodb_max_undo_log_size = @@GLOBAL.innodb_page_size * 4294967296;
 SET GLOBAL innodb_undo_log_truncate = 1;
 commit;
 disconnect con1;
@@ -33,6 +34,8 @@ commit;
 disconnect con2;
 connection default;
 SET GLOBAL innodb_max_purge_lag_wait=0;
+SET GLOBAL innodb_max_undo_log_size=DEFAULT;
+SET GLOBAL innodb_max_purge_lag_wait=0;
 set global innodb_fast_shutdown=0;
 # restart
 drop table t1, t2;

mysql-test/suite/innodb/t/undo_truncate.test

@@ -42,6 +42,7 @@ connection con1; reap; send delete from t1;
 connection con2; reap; delete from t2;
 connection con1; reap;
 
+SET GLOBAL innodb_max_undo_log_size = @@GLOBAL.innodb_page_size * 4294967296;
 SET GLOBAL innodb_undo_log_truncate = 1;
 commit; disconnect con1;
 connection con2; commit; disconnect con2;
@@ -52,6 +53,8 @@ connection default;
 let $trx_before= `SHOW ENGINE INNODB STATUS`;
 let $trx_before= `select substr('$trx_before',9)+2`;
 
+SET GLOBAL innodb_max_purge_lag_wait=0;
+SET GLOBAL innodb_max_undo_log_size=DEFAULT;
 SET GLOBAL innodb_max_purge_lag_wait=0;
 set global innodb_fast_shutdown=0;
 --source include/restart_mysqld.inc

storage/innobase/trx/trx0purge.cc

@@ -669,7 +669,9 @@ fil_space_t *purge_sys_t::truncating_tablespace()
   if (space || srv_undo_tablespaces_active < 2 || !srv_undo_log_truncate)
     return space;
 
-  const ulint size= ulint(srv_max_undo_log_size >> srv_page_size_shift);
+  const uint32_t size=
+    uint32_t(std::min(ulonglong{std::numeric_limits<uint32_t>::max()},
+                      srv_max_undo_log_size >> srv_page_size_shift));
   for (ulint i= truncate_undo_space.last, j= i;; )
   {
     if (fil_space_t *s= undo_truncate_try(srv_undo_space_id_start + i, size))