git: openjdk/loom: fibers: Fix issues when debugging without vthread debugging support enabled (launching the debug agent with virtualthreads=n).

[duke]

Changeset: fe20e215
Author:    Chris Plummer <chris.plummer at oracle.com>
Date:      2020-12-15 03:32:29 +0000
URL:       https://git.openjdk.java.net/loom/commit/fe20e215

Fix issues when debugging without vthread debugging support enabled (launching the debug agent with virtualthreads=n).

! src/jdk.jdwp.agent/share/native/libjdwp/debugInit.c
! src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c
! src/jdk.jdwp.agent/share/native/libjdwp/threadControl.c