git: openjdk/loom: fibers: Fix build errors in the libFiberTest.c

[duke]

Changeset: f5afccc7
Author:    Serguei Spitsyn <serguei.spitsyn at oracle.com>
Date:      2019-09-12 18:59:48 +0000
URL:       https://github.com/openjdk/loom/commit/f5afccc7

Fix build errors in the libFiberTest.c

! test/hotspot/jtreg/serviceability/jvmti/FiberTest/libFiberTest.c