RFR: Fix shenandoah jdk non-PCH build

[Roman Kennke]

Am 13.03.2018 um 16:43 schrieb Zhengyu Gu:
> The patch to fix shenandoah jdk build with precompiled header disabled.
> 
> Webrev:
> http://cr.openjdk.java.net/~zgu/shenandoah/sh-jdk-non-PCH/webrev.00/
> 
> 
> Test:
> 
>   hotspot_gc_shenandoah (fastdebug and release)
> 
> Thanks,
> 
> -Zhengyu

There are a few changes outside Shenandoah files. Why are they needed?
Why are they not needed upstream? Would it make sense to upstream them?

Roman