RFR: Fix shared tests to run without Shenandoah

[Aleksey Shipilev]

On 11/28/18 8:23 PM, Roman Kennke wrote:
> Let's do it like this (like line above):
> 
> * @requires !(vm.gc == "Shenandoah" & vm.opt.ExplicitGCInvokesConcurrent
> == true)
> 
> Ok? I find this still slightly confusing (as does Leonid), but seems ok:
> 
> http://cr.openjdk.java.net/~rkennke/fix-shared-tests/webrev.03/

Good! Phew.

-Aleksey

P.S. /r/ULPT: "You don't need to fix tests, if you have no tests".