MD5 production: Switch to Unix variant as the release is built on a Unix.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/commons/branches/commons-1_3@633128 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/build.xml b/build.xml
index 8b7f758..a311bfd 100644
--- a/build.xml
+++ b/build.xml
@@ -627,8 +627,8 @@
   </target>
 
   <target name="md5">
-    <property name="md5.exec" value="md5"/>
-    <property name="md5.options" value="-q"/>
+    <property name="md5.exec" value="md5sum"/>
+    <property name="md5.options" value=""/>
     <exec executable="${md5.exec}" output="${sign.archive}.md5">
       <arg line="${md5.options} ${sign.archive}"/>
     </exec>