When commit df2943ba moved "rm -f qemu-options.def" from distclean
to clean, it also added "rm -f $$d/qemu-options.def" to the for d in
$(ALL_SUBDIRS) loop.  That file doesn't exist.  Remove the mistaken
rm.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190528082308.22032-3-armbru@redhat.com>