Add missing doPriv around getting the handler service

Pulls in Equinox fix eclipse-equinox/equinox#684

dev/org.eclipse.osgi/src/org/eclipse/osgi/internal/url/URLStreamHandlerProxy.java

@@ -234,7 +234,7 @@ synchronized void dispose() {
 		@Override
 		public synchronized URLStreamHandlerService get() {
 			if (service == null && !disposed) {
-				service = bundleContext.getService(reference);
+				service = URLStreamHandlerFactoryImpl.secureAction.getService(reference, bundleContext);
 			}
 			return service;
 		}