Make source-build from a fresh repository work, compile-lib was not created.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1678322 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -406,6 +406,7 @@ under the License.
     	<!-- remove previous versions of third-party jars to prevent them from lingering around, 
     		we often had hard-to-find build/CI-problems because of these! -->
 		<mkdir dir="${main.lib}"/>
+		<mkdir dir="${compile.lib}"/>
 		<delete verbose="true">
 			<fileset dir="${main.lib}">
 	    		<include name="ant-1.8*"/>