Do deactiving and runaway detecting before ReadyForQuery()

This fixes issue #4022, so any OOM errors of current query
will not muddle following queries.

src/backend/tcop/postgres.c

@@ -4889,6 +4889,13 @@ PostgresMain(int argc, char *argv[],
         if (Gp_role == GP_ROLE_EXECUTE)
             gp_command_count = 0;
 
+		/*
+		 * Do deactiving and runaway detecting before ReadyForQuery(),
+		 * so any OOM errors of current query will not muddle following
+		 * queries
+		 */
+		IdleTracker_DeactivateProcess();
+
 		/*
 		 * (1) If we've reached idle state, tell the frontend we're ready for
 		 * a new query.
@@ -4968,7 +4975,6 @@ PostgresMain(int argc, char *argv[],
 					elog(FATAL, "could not set timer for client wait timeout");
 		}
 
-		IdleTracker_DeactivateProcess();
 		firstchar = ReadCommand(&input_message);
 		IdleTracker_ActivateProcess();