RFR: Fix Shenandoah 8u build issues

[Roman Kennke]

Am 16.05.2018 um 19:10 schrieb Zhengyu Gu:
> Other than build problems reported by Michal, moving heuristics to sub
> directory also breaks build on Windows.
> 
> Webrev:
> http://cr.openjdk.java.net/~zgu/shenandoah/sh-jdk8u-build/webrev.00/
> 
> Tested build on Windows 64 and Linux 64.
> 
> Thanks,
> 
> -Zhengyu

Uhh. Ok. Please push it.

I guess it makes sense to append it to The Big Merge too?

Roman