RFR: JDK-8172312 Update docs target and image for new combined docs

Thu Mar 30 13:05:43 UTC 2017

As a part of JEP 299, we should build the Javadoc as a single combined 
output, instead of a dozen or so individual javadoc bundles. This bug 
fixes this. The selection on what to include is now based on modules 
instead of packages.

The fix in MakeBase.gmk is to keep CacheFind quiet if the src dir(s) 
does not exist, otherwise find can emit an error message. (This was 
provoked by the new call to SetupZipArchive).

The module selection has been contributed by Mandy Chang.

I intend to push this to JDK9. Since this is a noreg-doc bug, no special 
RDP2 process is required.

Bug: https://bugs.openjdk.java.net/browse/JDK-8172312
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8172312-combined-javadocs/webrev.01

/Magnus