Detect OpenJDK7 and Harmony (not that we'd use it for now)

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@1037654 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -352,7 +352,10 @@
     <property name="ignoresystemclasses" value="false"/>
     <available property="jdk1.5+" classname="java.net.Proxy"/>
     <available property="jdk1.6+" classname="java.util.ServiceLoader"/>
+    <available property="jdk1.7+" classname="java.nio.file.FileSystem"/>
     <available property="kaffe" classname="kaffe.util.NotImplemented"/>
+    <available property="harmony"
+               classname="org.apache.harmony.luni.util.Base64"/>
     <available property="bsf.present"
       classname="org.apache.bsf.BSFManager"
       classpathref="classpath" ignoresystemclasses="${ignoresystemclasses}"/>