git: openjdk/loom: fibers: Fix build

[duke]

Changeset: 639a2c16
Author:    Ron Pressler <ron.pressler at oracle.com>
Date:      2020-01-10 12:52:58 +0000
URL:       https://git.openjdk.java.net/loom/commit/639a2c16

Fix build

! src/hotspot/share/runtime/continuation.cpp