hg: jigsaw/jake/langtools: add missing file

[jonathan . gibbons]

Changeset: 86ed8a85486d
Author:    vromero
Date:      2015-09-14 18:23 -0700
URL:       http://hg.openjdk.java.net/jigsaw/jake/langtools/rev/86ed8a85486d

add missing file

+ src/jdk.compiler/share/classes/com/sun/tools/javac/util/ModuleHelper.java