pstools: allow either wow6432node or native key in reg check

I've not figured out why nsis might use wow64232node but it does. So
I'll accept either variant of the reg key as a sign of successful
installation.

packages/pstools.xml

@@ -4,8 +4,12 @@
     <variable name="version" value="2.45.1" />
 
     <!-- N.B. the installer takes care of creating and removing this reg key as needed -->
-    <check type='registry' condition='equals' path='HKLM\software\ucam_wpkg.cam.ac.uk\pstools\version' value="%version%"/>
-
+    <!-- I've not figured out why NSIS sometimes puts the key in wow6432node though so
+         we'll accept either reg key existing -->
+    <check type="logical" condition="or">
+      <check type='registry' condition='equals' path='HKLM\software\ucam_wpkg.cam.ac.uk\pstools\version' value="%version%"/>
+      <check type='registry' condition='equals' path='HKLM\software\wow6432node\ucam_wpkg.cam.ac.uk\pstools\version' value="%version%"/>
+    </check>
     <!-- the exe is built by https://gitlab.developers.cam.ac.uk/ch/co/wpkg/pstools-nsis; see README contained therein -->
 
     <install cmd='%wpkgsoftware%\microsoft.com\pstools\pstools-%version%.exe' />