RFR (XXS) 8213767: Remove the -Xconcurrentio flag and associated code

[Lois Foltan]

Looks good.
Lois

On 11/13/2018 8:51 PM, David Holmes wrote:
> Bug: https://bugs.openjdk.java.net/browse/JDK-8213767
> CSR: https://bugs.openjdk.java.net/browse/JDK-8213768
>
> webrev: http://cr.openjdk.java.net/~dholmes/8213767/webrev/
>
>
> This flag dates back to the JDK 1.2/1.3 days and was useful primarily 
> on Solaris where it enabled use of LWP synchronization. But that 
> became the default in JDK 1.4. The flag serves no useful purpose and 
> is unlikely to have been used for many years.
>
> Thanks,
> David