If we cannot build Javadoc, we cannot copy it to the dist dir either.

https://hudson.apache.org/hudson/view/Ant/job/Ant_Nightly/151/console
javadoc_check:
-javadocs.do:
-javadocs.dont:
     [echo] Javadoc creation of Ant's API does not work with JDK 1.4. Please use a newer one.
javadocs:
dist_javadocs:
    [mkdir] Created dir: .../apache-ant-1.8.2alpha/docs/manual/api
BUILD FAILED
.../build.xml:1086: The following error occurred while executing this line:
.../build.xml:850: .../build/javadocs not found.


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@999504 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -845,7 +845,7 @@
     </antcall>
   </target>
 
-  <target name="dist_javadocs" depends="javadocs">
+  <target name="dist_javadocs" depends="javadocs" if="jdk1.5+">
     <mkdir dir="${dist.javadocs}"/>
     <copy todir="${dist.javadocs}" overwrite="true">
       <fileset dir="${build.javadocs}"/>