[gentoo-java] Improvements to javadoc handling

[Petteri Räty]

With the attached patch that I just committed dojavadoc will create an
api symlink to /usr/share/<pkg>-<slot> if you have USE="doc" and the
package installs javadocs using dojavadoc. This way it stays the same
between revisions which is easier for ides like Netbeans and Eclipse.
You could also do this with the Portage DOC_SYMLINKS_DIR feature but I
find it quite nice to provide everything Java in the same directory for
the package so you have to browse only one directory in your IDE. The
same patch also adds support for --symlink for ebuild writes. That way
we don't have to break html links that expect the api directory to be
named in some specific way.

Regards,
Petteri