Broken compilation for newer JDKs

[akks]

Adding JAXB-generated classes in r7133 leads to the problem with JDK8:

svn co https://josm.openstreetmap.de/svn/trunk
cd trunk
ant dist 

gives the following exception:

BUILD FAILED
F:\Java\trunk\build.xml:207: java.lang.AssertionError: org.xml.sax.SAXParseException; systemId: jar:file:/F:/Java/trunk/tools/jaxb/jaxb-xjc.jar!/com/sun/tools/xjc/reader/xmlschema/bindinfo/binding.xsd; lineNumber: 52; columnNumber: 88; schema_reference: Failed to read schema document 'xjc.xsd', because 'file' access is not allowed due to restriction set by the accessExternalSchema property. 

The problem is known for newer JDKs (security reasons), but I could not solve it by adding <arg value="-disableXmlSecurity" />.