qemu-tech: Fix dangling @menu entries

Recent commit 2f2c4e4 "Convert "translator internals" docs to RST,
move to devel manual" and commit 282d36b "qemu-tech.texi: Remove
"QEMU compared to other emulators" section" removed @node, but left
their @menu entries behind.  This broke building qemu-doc.info (but
not qemu-doc.{html,pdf,txt}; how odd).  Bury the dead @menu entries.

Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Fixes: 2f2c4e4
Fixes: 282d36b
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190715055736.15214-3-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

qemu-tech.texi

@@ -3,10 +3,7 @@
 
 @menu
 * CPU emulation::
-* Translator Internals::
-* QEMU compared to other emulators::
 * Managed start up options::
-* Bibliography::
 @end menu
 
 @node CPU emulation