FYI: Ensure metadata alive for Shenandoah too

[Roman Kennke]

I pushed the following fix. It fixes an occasional assert about a root
object not being marked.

diff --git a/src/share/vm/ci/ciObjectFactory.cpp
b/src/share/vm/ci/ciObjectFactory.cpp
--- a/src/share/vm/ci/ciObjectFactory.cpp
+++ b/src/share/vm/ci/ciObjectFactory.cpp
@@ -413,7 +413,7 @@
   ASSERT_IN_VM; // We're handling raw oops here.
 
 #if INCLUDE_ALL_GCS
-  if (!UseG1GC) {
+  if (!(UseG1GC || UseShenandoahGC)) {
     return;
   }
   Klass* metadata_owner_klass;