RFR (S) 8245942: Shenandoah: x86_32 builds fail after JDK-8245594

[Aleksey Shipilev]

Bug:
  https://bugs.openjdk.java.net/browse/JDK-8245942

JDK-8245594 removed some volatile-qualified members, so now x86_32 build fails. I believe we just
turn the affected classes trivially copyable as well, like it was done for ShenandoahVerifierTask in
JDK-8245594.

Fix:
  https://cr.openjdk.java.net/~shade/8245942/webrev.01/

Kim, does that match original intent with JDK-8245594?

Testing: hotspot_gc_shenandoah {x86_64, x86_32}

-- 
Thanks,
-Aleksey