sh/jdk8 windows builds failure

[Aleksey Shipilev]

In sh/jdk8, current Windows build fails:
 https://builds.shipilev.net/openjdk-shenandoah-jdk8/build-logs/build-windows-x86_64-fastdebug.log

C:\buildbot\worker\build-shenandoah-jdk8-windows\build\hotspot\src\share\vm\gc_implementation\shenandoah\shenandoahRootProcessor.cpp(76)
: error C3083: '{ctor}': the symbol to the left of a '::' must be a type

...because there is double qualification here:
  https://hg.openjdk.java.net/shenandoah/jdk8/hotspot/rev/c18245ae4adf#l7.64

Zhengyu, please fix that when reapplying the backports.

-- 
Thanks,
-Aleksey