RFR [15] 8224613: javadoc should better handle bad options

[Pavel Rappo]

Hello,

Please review the change for https://bugs.openjdk.java.net/browse/JDK-8224613

  http://cr.openjdk.java.net/~prappo/8224613/webrev.00/

This addresses a scenario in which a doclet failure was previously overlooked. More specifically, if a doclet returned false after processing one or more of its options while otherwise staying silent, the tool continued its execution.

-Pavel