NAnt doc build test fix

Index: NAnt.build
===================================================================
RCS file: /cvsroot/nant/nant/NAnt.build,v
retrieving revision 1.278
diff -u -r1.278 NAnt.build
--- NAnt.build  26 Sep 2011 00:10:20 -0000  1.278
+++ NAnt.build  1 Oct 2011 22:48:00 -0000
@@ -332,6 +332,7 @@
             </resources>
         </csc>
         <echo message="Creating task and type documentation from ${build.dir}/bin" />
+        <xmlpoke file="${build.dir}/bin/${nant.console.name}.exe.config" xpath="/configuration/runtime/NetFx40_LegacySecurityPolicy/@enabled" value="true" />
         <exec program="${build.dir}/bin/${nant.console.name}.exe" managed="true">
             <arg value="-indent:1" />
             <arg value="-buildfile:NAnt.build" />
@@ -341,6 +342,7 @@
             <arg value="${project.config}" />
             <arg value="self-userdoc" />
         </exec>
+        <xmlpoke file="${build.dir}/bin/${nant.console.name}.exe.config" xpath="/configuration/runtime/NetFx40_LegacySecurityPolicy/@enabled" value="false" />
     </target>
     <target name="self-userdoc" depends="init">
         <!-- use ndoc and NAnt.Documenter to build user doc if they need it -->