RFR: 8151542: URL resources for multi-release jar files have a #runtime fragment appended to them

[Steve Drach]

Issue: https://bugs.openjdk.java.net/browse/JDK-8151542 <https://bugs.openjdk.java.net/browse/JDK-8151542>

Webrev: http://cr.openjdk.java.net/~sdrach/8151542/webrev/ <http://cr.openjdk.java.net/~sdrach/8151542/webrev/>

This changeset causes the URL returned from a ClassLoader.getResource(name) invocation to be reified, that is the URL is a direct pointer to either a versioned or unversioned entry in the jar file. The patch also assures that jar URL’s are always processed by the URLClassPath.JarLoader.  The MultiReleaseJarURLConnection test was enhanced to demonstrate that reified URLs are returned.  The SimpleHttpServer test helper class was moved into it’s own file.