[patch] always set the jdk docs target

[Lillian Angel]

Matthias Klose wrote:
> setting JDK_UPDATE_VERSION in the environment had the side effect of disabling
> the docs build. Make the docs target independent of JDK_UPDATE_VERSION, it can
> still be disabled with setting NO_DOCS.
>
> The build doesn't fail, so maybe some packages don't have the docs included.
>   

Thanks. Go ahead and commit this.


Lillian