hg: jdk/submit: 8213767: Remove the -Xconcurrentio flag and associated code

[david.holmes at oracle.com]

Changeset: 6f18c23b0185
Author:    dholmes
Date:      2018-11-14 04:56 -0500
URL:       http://hg.openjdk.java.net/jdk/submit/rev/6f18c23b0185

8213767: Remove the -Xconcurrentio flag and associated code
Reviewed-by: lfoltan, rehn

! src/hotspot/share/runtime/arguments.cpp
! src/hotspot/share/runtime/safepoint.hpp
! test/hotspot/jtreg/runtime/CommandLine/TestNullTerminatedFlags.java