RFR(trivial): 8233574: Shenandoah: build is broken without jfr

[Roman Kennke]

Hi Jie,

the change looks good (and trivial), thank you!

Roman

> Hi all,
> 
> May I get reviews for the one-line change?
> This bug was found while I was testing David's patch for JDK-8233454 [1].
> 
> JBS:    https://bugs.openjdk.java.net/browse/JDK-8233574
> Webrev: http://cr.openjdk.java.net/~jiefu/8233574/webrev.00/
> 
> Thanks a lot.
> Best regards,
> Jie
> 
> [1]
> https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-November/036788.html
> 
> 
>