Support Shenandoah and ZGC (#4)

Bazel currently refuses to start up when JVM is launched with `-XX:+UseShenandoahGC` or
`-XX:+UseZGC`. This can be easily fixed by making `RetainedHeapLimiter` recognize the
memory pool name `Shenandoah` and `ZHeap`.

Upstream: bazelbuild#12644

src/main/java/com/google/devtools/build/lib/runtime/RetainedHeapLimiter.java

@@ -183,6 +183,8 @@ private static boolean isTenuredSpace(String name) {
     return "CMS Old Gen".equals(name)
         || "G1 Old Gen".equals(name)
         || "PS Old Gen".equals(name)
-        || "Tenured Gen".equals(name);
+        || "Tenured Gen".equals(name)
+        || "Shenandoah".equals(name)
+        || "ZHeap".equals(name);
   }
 }