git: openjdk/loom: fibers: Fix null pointer in squash

[duke]

Changeset: 0b63512b
Author:    Ron Pressler <ron.pressler at oracle.com>
Date:      2020-08-14 10:18:35 +0000
URL:       https://git.openjdk.java.net/loom/commit/0b63512b

Fix null pointer in squash

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