trnman_destroy returns void, remove unused variables

storage/maria/trnman.h:
  trnman_destroy returns void

storage/maria/trnman.c

@@ -124,7 +124,7 @@ int trnman_init()
     this could only be called in the "idle" state - no transaction can be
     running. See asserts below.
 */
-int trnman_destroy()
+void trnman_destroy()
 {
   DBUG_ASSERT(trid_to_committed_trn.count == 0);
   DBUG_ASSERT(trnman_active_transactions == 0);
@@ -265,7 +265,6 @@ TRN *trnman_new_trn(pthread_mutex_t *mutex, pthread_cond_t *cond)
 */
 void trnman_end_trn(TRN *trn, my_bool commit)
 {
-  int res;
   TRN *free_me= 0;
   LF_PINS *pins= trn->pins;
 
@@ -303,8 +302,9 @@ void trnman_end_trn(TRN *trn, my_bool commit)
   */
   if (commit && active_list_min.next != &active_list_max)
   {
-    trn->commit_trid= global_trid_generator;
+    int res;
 
+    trn->commit_trid= global_trid_generator;
     trn->next= &committed_list_max;
     trn->prev= committed_list_max.prev;
     committed_list_max.prev= trn->prev->next= trn;
@@ -330,11 +330,10 @@ void trnman_end_trn(TRN *trn, my_bool commit)
 
   while (free_me) // XXX send them to the purge thread
   {
-    int res;
     TRN *t= free_me;
     free_me= free_me->next;
 
-    res= lf_hash_delete(&trid_to_committed_trn, pins, &t->trid, sizeof(TrID));
+    lf_hash_delete(&trid_to_committed_trn, pins, &t->trid, sizeof(TrID));
 
     trnman_free_trn(t);
   }

storage/maria/trnman.h

@@ -44,7 +44,7 @@ struct st_transaction
 extern uint trnman_active_transactions, trnman_allocated_transactions;
 
 int trnman_init(void);
-int trnman_destroy(void);
+void trnman_destroy(void);
 TRN *trnman_new_trn(pthread_mutex_t *mutex, pthread_cond_t *cond);
 void trnman_end_trn(TRN *trn, my_bool commit);
 #define trnman_commit_trn(T) trnman_end_trn(T, TRUE)