Enable OpenJ9 builds of JDK-Next (15) (#1815)
Enable OpenJ9 builds of JDK-Next (15) (#1815)

Signed-off-by: Morgan Davies <467cf9e87a742b793386ba461f58babccc5fdd97@ibm.com>
AdoptOpenJDK/openjdk-build,AdoptOpenJDK/openjdk-build,karianna/openjdk-build,karianna/openjdk-build