RFR: Save both IU and FPU state in WB stub around runtime call

[Aleksey Shipilev]

On 11/20/18 2:19 PM, Roman Kennke wrote:
> http://cr.openjdk.java.net/~rkennke/fixwbstub/webrev.00/

*) It is unfortunate we have to restore %rax and do the RB part of WB on this path. I don't see an
easy way out, though. Please put the comment near RB on rax:
  // Need to restore the WB result, which have to be the forwarded object.

*) Nit: movq vs. mov:
  899   __ movq(rbp, rsp);
  ...
  907   __ mov(rsp, rbp);

Otherwise looks okay.

-Aleksey