Remove duplicate build target

Review at http://gwt-code-reviews.appspot.com/1423812

Review by: rjrjr@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10120 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/build.xml b/build.xml
index 5455b80..81a956a 100755
--- a/build.xml
+++ b/build.xml
@@ -40,7 +40,6 @@
     <call-subproject subproject="requestfactory" subtarget="build" />
     <call-subproject subproject="servlet" subtarget="build" />
     <call-subproject subproject="jni" subtarget="build" />
-    <call-subproject subproject="requestfactory" subtarget="build" />
   </target>
 
   <target name="dist" depends="build, doc" description="[action] Make all the distributions">