Fixed main.implicit_commit ASAN failure

InnoDB mutex monitor is accessing mutexes of poisoned (cached) trx
objects. Unpoison ReadView::m_mutex similarly to trx_t::mutex.

This is regression after MDEV-22593.

storage/innobase/include/read0types.h

@@ -276,5 +276,22 @@ class ReadView: public ReadViewBase
       to->append(*this);
     mutex_exit(&m_mutex);
   }
+
+
+  /**
+    Unpoison the memory for innodb_monitor_set_option;
+    It is operating also on the freed transaction objects.
+    Declare the contents as initialized for Valgrind;
+    We checked that it was initialized in trx_pools->mem_free(trx).
+  */
+  void mem_valid() const
+  {
+#ifdef __SANITIZE_ADDRESS__
+    MEM_UNDEFINED(&m_mutex, sizeof m_mutex);
+#endif
+#ifdef HAVE_valgrind
+    UNIV_MEM_VALID(&m_mutex, sizeof m_mutex);
+#endif
+  }
 };
 #endif

storage/innobase/trx/trx0trx.cc

@@ -457,6 +457,7 @@ void trx_free(trx_t*& trx)
 	/* Declare the contents as initialized for Valgrind;
 	we checked that it was initialized in trx_pools->mem_free(trx). */
 	UNIV_MEM_VALID(&trx->mutex, sizeof trx->mutex);
+	trx->read_view.mem_valid();
 
 	trx = NULL;
 }