Please review a simple change to javadoc, to accept and ignore --add-opens. This brings javadoc into line with the module-related options supported by java and javac.
The option is simply delegated to javac, for it to handle (ignore) the option.
Like javac, the option is undocumented/hidden. Tests are added to ensure that the option is accepted and does not otherwise impact javadoc operation. JBS: https://bugs.openjdk.java.net/browse/JDK-8181878 Webrev: http://cr.openjdk.java.net/~jjg/8181878/webrev.00/ -- Jon
