tests/avocado/tuxrun_baselines: Fix ppc64 tests for binaries without slirp

The ppc64 tuxrun tests are currently failing if "slirp" has been
disabled in the binary since they are using "-netdev user" now.
We have to skip the test if this network backend is missing.

Fixes: 6ee3624236 ("improve code coverage for ppc64")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230606192802.666000-1-thuth@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
diff --git a/tests/avocado/tuxrun_baselines.py b/tests/avocado/tuxrun_baselines.py
index 3a46e7a..e12250e 100644
--- a/tests/avocado/tuxrun_baselines.py
+++ b/tests/avocado/tuxrun_baselines.py
@@ -184,6 +184,7 @@ def common_tuxrun(self,
 
     def ppc64_common_tuxrun(self, sums, prefix):
         # add device args to command line.
+        self.require_netdev('user')
         self.vm.add_args('-netdev', 'user,id=vnet,hostfwd=:127.0.0.1:0-:22',
                          '-device', 'virtio-net,netdev=vnet')
         self.vm.add_args('-netdev', '{"type":"user","id":"hostnet0"}',