MDEV-14609 XA Transction unable to ROLLBACK TO SAVEPOINT

The function trans_rollback_to_savepoint(), unlike trans_savepoint(),
did not allow xa_state=XA_ACTIVE, so an attempt to do ROLLBCK TO SAVEPOINT
inside an XA transaction incorrectly returned an error
"...command cannot be executed ... in the ACTIVE state...".

Partially merging a MySQL patch:
  7fb5c47390311d9b1b5367f97cb8fedd4102dd05
  This is WL#7193 (Decouple THD and st_transactions)...

The currently merged part includes these changes:
- Introducing st_xid_state::check_has_uncommitted_xa()
- Reusing it in both trans_rollback_to_savepoint() and trans_savepoint(),
  so now both allow XA_ACTIVE.

1 files changed, 2 insertions, 10 deletions

diff --git a/sql/transaction.cc b/sql/transaction.cc
index ae38e920a1d..6b09bd18d4c 100644
--- a/sql/transaction.cc
+++ b/sql/transaction.cc
@@ -433,12 +433,8 @@ bool trans_savepoint(THD *thd, LEX_STRING name)
       !opt_using_transactions)
     DBUG_RETURN(FALSE);
 
-  enum xa_states xa_state= thd->transaction.xid_state.xa_state;
-  if (xa_state != XA_NOTR && xa_state != XA_ACTIVE)
-  {
-    my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
+  if (thd->transaction.xid_state.check_has_uncommitted_xa())
     DBUG_RETURN(TRUE);
-  }
 
   sv= find_savepoint(thd, name);
 
@@ -513,12 +509,8 @@ bool trans_rollback_to_savepoint(THD *thd, LEX_STRING name)
     DBUG_RETURN(TRUE);
   }
 
-  enum xa_states xa_state= thd->transaction.xid_state.xa_state;
-  if (xa_state != XA_NOTR)
-  {
-    my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
+  if (thd->transaction.xid_state.check_has_uncommitted_xa())
     DBUG_RETURN(TRUE);
-  }
 
   if (ha_rollback_to_savepoint(thd, sv))
     res= TRUE;