[javadoc] Error processing sources with -private

Enabling -private for JDK API docs via

diff --git a/common/makefiles/javadoc/Javadoc.gmk b/common/makefiles/javadoc/Javadoc.gmk
--- a/common/makefiles/javadoc/Javadoc.gmk
+++ b/common/makefiles/javadoc/Javadoc.gmk
@@ -403,6 +403,7 @@ coredocs: $(COREAPI_INDEX_FILE)
           $(call OptionPair,-tag,see ) ; \
           $(call OptionPair,-tag,$(TAG_JLS)) ; \
          $(call OptionOnly,-splitIndex) ; \
+ $(call OptionOnly,-private) ; \
          $(call OptionPair,-overview,$(COREAPI_OVERVIEW)) ; \
          $(call OptionPair,-doctitle,$(COREAPI_DOCTITLE)) ; \
          $(call OptionPair,-windowtitle,$(COREAPI_WINDOWTITLE) $(DRAFT_WINTITLE)) ;\


Reveals several parsing errors with well formed JDK sources:

jdk/src/share/classes/java/lang/Object.java:37: error: missing method body, or declare abstract
public class Object {
       ^

jdk/src/share/classes/java/lang/Object.java:148: error: missing method body, or declare abstract
    public boolean equals(Object obj) {
                   ^

jdk/lambda/build/linux-x86_64-normal-server-fastdebug/jdk/gensrc/java/lang/UNIXProcess.java:123: error: missing method body, or declare abstract
            public Executor run() {

/jdk/src/share/classes/java/util/ResourceBundle.java:471: error: missing method body, or declare abstract
                    new PrivilegedAction<RBClassLoader>() {
                                                          ^

jdk/src/share/classes/java/rmi/server/RMIClassLoader.java:119: error: missing method body, or declare abstract
            new PrivilegedAction<RMIClassLoaderSpi>() {

This doesn't cause any specific problems for my current usage but probably should be investigated.