Use libcore/known_oj_tags for the javadoc stage.

Helps us process (and discard) OpenJdk specific javadoc tags.

(cherry-picked from e03d5e477b47e4ac8e227d649afd4ffe89f23712)

Change-Id: I35287e9b56c148eb6cd8f37d7df81920d0d8a3bb
1 file changed