RFR (XS) 8242040: Shenandoah: print allocation failure type

[Roman Kennke]

Ok.

Thank you!
Roman

> RFE:
>   https://bugs.openjdk.java.net/browse/JDK-8242040
> 
> Webrev:
>   http://cr.openjdk.java.net/~shade/8242040/webrev.01/
> 
> Testing: hotspot_gc_shenandoah, eyeballing gc logs
>