hg: openjfx/8/graphics/rt: gradle build: fix missing slash in optional .classpath entry

[hang.vo at oracle.com]

Changeset: 489b9ef10dce
Author:    snorthov
Date:      2013-06-17 09:06 -0400
URL:       http://hg.openjdk.java.net/openjfx/8/graphics/rt/rev/489b9ef10dce

gradle build: fix missing slash in optional .classpath entry

! build.gradle