hg: loom/loom: Fix build issue with uninitialized variable in DoContinueSingleStepTest

[markus.gronlund at oracle.com]

Changeset: 73a32d202b27
Author:    mgronlun
Date:      2019-06-10 17:04 +0200
URL:       http://hg.openjdk.java.net/loom/loom/rev/73a32d202b27

Fix build issue with uninitialized variable in DoContinueSingleStepTest

! test/hotspot/jtreg/serviceability/jvmti/DoContinueSingleStepTest/libDoContinueSingleStepTest.cpp