[vector] Fix the issue that unslice modifies the argument vector

[Paul Sandoz]

+1

Paul.

> On Oct 21, 2019, at 7:38 PM, Yang Zhang (Arm Technology China) <Yang.Zhang at arm.com> wrote:
> 
> Hi all
> 
> Could anyone please help to review this patch?
> 
> Webrev: http://cr.openjdk.java.net/~yzhang/vectorapi/vectorapi.unslice/webrev.00/
> 
> In this patch, I fix the issue that unsliced modifies the argument vector. The reason why change the name of getElements() to vec() is described in
> previous email thread.
> https://mail.openjdk.java.net/pipermail/panama-dev/2019-September/006389.html 
> 
> Regards,
> Yang