[vector] RFR: Fix FMA intrinsic

[Paul Sandoz]

Looks good to me,
Paul.

> On May 17, 2018, at 1:04 AM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~vlivanov/panama/vector/fma/webrev.00/
> 
> There are 2 bug being fixed:
>  (1) 3rd argument of a ternary operation is always null in intrinsified version;
> 
>  (2) VectorNode::make() accepts vector ops, but misses Op_FmaVF/Op_FmaVD in ternary case. Instead of adding them into the list, I propose to always pass scalar ops into the methods and get rid of the special cases for vector ops.
> 
> Thanks!
> 
> Best regards,
> Vladimir Ivanov