hg: jdk/sandbox: 8222482: [Graal] Update java-allocation-instrumenter.jar handling in graalunit README.md

[chris.hegarty at oracle.com]

Changeset: 508285c7c6f7
Author:    epavlova
Date:      2019-05-21 12:29 -0700
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/508285c7c6f7

8222482: [Graal] Update java-allocation-instrumenter.jar handling in graalunit README.md
Reviewed-by: kvn, shade

! test/hotspot/jtreg/compiler/graalunit/README.md
+ test/hotspot/jtreg/compiler/graalunit/downloadLibs.sh