RFR: JDK-8221598 - Update Graal

[jesper.wilhelmsson at oracle.com]

Hi,

Please review the patch to integrate recent Graal changes into OpenJDK.
Graal tip to integrate: 20f370437efb6b2a3f455a238da6141dc101d38c

Bug: https://bugs.openjdk.java.net/browse/JDK-8221598
Webrev: http://cr.openjdk.java.net/~jwilhelm/8221598/webrev.00/

Thanks,
/Jesper