MDEV-29187: Deadlock output in InnoDB status always shows transaction (0)

At some point the incrementing of the transaction counter got dropped.

Thanks Agustin for the bug report.

storage/innobase/lock/lock0lock.cc

@@ -6126,6 +6126,7 @@ namespace Deadlock
       for (trx_t *next= cycle;;)
       {
         next= next->lock.wait_trx;
+        l++;
         const undo_no_t next_weight= TRX_WEIGHT(next) |
           (next->mysql_thd &&
 #ifdef WITH_WSREP