git: openjdk/loom: fibers: Fix stack walk

[duke]

Changeset: 0b345c12
Author:    Ron Pressler <ron.pressler at oracle.com>
Date:      2020-08-06 17:30:39 +0000
URL:       https://git.openjdk.java.net/loom/commit/0b345c12

Fix stack walk

! src/hotspot/share/runtime/continuation.cpp
! test/jdk/java/lang/Continuation/Fuzz.java