hg: jdk/sandbox: 8236921: Add build target to produce a JDK image suitable for a Graal/SVM build

[chris.hegarty at oracle.com]

Changeset: 786a4824dba3
Author:    sgehwolf
Date:      2019-12-16 11:06 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/786a4824dba3

8236921: Add build target to produce a JDK image suitable for a Graal/SVM build
Summary: make graal-builder-image will produce a suitable build JDK
Reviewed-by: erikj

+ make/GraalBuilderImage.gmk
! make/Main.gmk
! make/autoconf/spec.gmk.in