hg: jdk9/sandbox: ihse-javadoc-branch: Only use packages file if needed.

[magnus.ihse.bursie at oracle.com]

Changeset: fc791788ebd5
Author:    ihse
Date:      2016-11-17 14:40 +0100
URL:       http://hg.openjdk.java.net/jdk9/sandbox/rev/fc791788ebd5

ihse-javadoc-branch: Only use packages file if needed.

! make/Javadoc.gmk