hg: shenandoah/jdk9/hotspot: Make sure C2 arguments are not used when C2 is disabled.

[ashipile at redhat.com]

Changeset: 2ee664817f93
Author:    shade
Date:      2017-04-21 10:26 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk9/hotspot/rev/2ee664817f93

Make sure C2 arguments are not used when C2 is disabled.

! src/share/vm/runtime/arguments.cpp