Revert "Work with older versions of ant"

This reverts commit 1f299c403c.

The reverted commit prevents clover snapshotting working correctly
Build process will now require Ant >=1.6.3

Change-Id: I550308899cdabf2894c90cb345addf2c393efd6b
Reviewed-on: http://gerrit.dmdirc.com/771
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Gregory Holmes <greg@dmdirc.com>

build-tests.xml

@@ -89,9 +89,11 @@
     </target>
 
     <target name="-test-no-xvfb" unless="use.xvfb">
-        <antcall target="with.clover" />
-        <antcall target="do-real-test" />
-        <antcall target="clover.snapshot" />
+        <antcall>
+            <target>with.clover</target>
+            <target>do-real-test</target>
+            <target>clover.snapshot</target>
+        </antcall>
     </target>
 
     <target name="test-html" depends="with.clover,compile-test,test,clover.html,clover.snapshot"