inconsistent check of module-related options against target version

javac Arguments checking allows some module related options to be specified for use with older releases, but not others. This is inconsistent and should be fixed.

        checkOptionAllowed(t.compareTo(Target.JDK1_8) <= 0,
                option -> error("err.option.not.allowed.with.target", option.getPrimaryName(), t.name),
                Option.BOOT_CLASS_PATH,
                Option.XBOOTCLASSPATH_PREPEND, Option.XBOOTCLASSPATH, Option.XBOOTCLASSPATH_APPEND,
                Option.ENDORSEDDIRS, Option.DJAVA_ENDORSED_DIRS,
                Option.EXTDIRS, Option.DJAVA_EXT_DIRS);

        checkOptionAllowed(t.compareTo(Target.JDK1_9) >= 0,
                option -> error("err.option.not.allowed.with.target", option.getPrimaryName(), t.name),
                Option.MODULE_SOURCE_PATH, Option.UPGRADE_MODULE_PATH,
                Option.SYSTEM, Option.MODULE_PATH, Option.ADD_MODULES, Option.LIMIT_MODULES,
                Option.PATCH_MODULE);

The first block of checks are OK; these options should not be allowed with -target 9; the second block lists --add-modules but not --add-exports, --add-opens, --add-reads. Arguably, all should be allowed if using the platform modules, i.e. using older -release, or using older -target without -bootclasspath.