fixing syntax error, only one condition is supported inside the condition task

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@1591190 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -1204,8 +1204,10 @@
   </target>
 
   <condition property="buildosxpackage">
-    <os family="mac"/>
-    <isset property="buildosxpackage.required"/>
+    <and>
+       <os family="mac"/>
+       <isset property="buildosxpackage.required"/>
+    </and>
   </condition>
 
   <target name="pkg_distribution" depends="zip_distribution" if="buildosxpackage">