RFR(XS): ostream has unnecessary dependency on GCId

[Per Liden]

Looks good.

Per

On 2016-03-29 04:09, Kim Barrett wrote:
> Please review this small cleanup, eliminating a no longer
> needed #include dependency.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8152916
>
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8152916/webrev.00/
>
> Testing:
> JPRT
>