HADOOP-7457. build.xml correction.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.22@1175205 13f79535-47bb-0310-9956-ffa450edef68

common/build.xml

@@ -875,7 +875,7 @@
   
   <target name="docs" depends="forrest.check" description="Generate forrest-based documentation. 
        To use, specify -Dforrest.home=&lt;base of Apache Forrest installation&gt; on the command line." if="forrest.home">
-    <exec dir="${docs.src}" executable="${forrest.home}/bin/forrest.bat"
+    <exec dir="${docs.src}" executable="${forrest.home}/bin/forrest"
 	  failonerror="true">
     </exec>
     <copy todir="${build.docs}">