tests/qtest/rtl8139-test: Check whether the rtl8139 device is available

Though we are already using CONFIG_RTL8139_PCI in the meson.build file
for testing whether the rtl8139 device is available or not, this is not
enough: The CONFIG switch might have been selected by another target
(e.g. the mips fuloong2e machine has the rtl8139 chip soldered on the
board), so CONFIG_RTL8139_PCI ends up in config_all_devices and the
test then gets executed on x86. We need an additional run-time check
to be on the safe side to make this test also work when configure has
been run with "--without-default-devices".

Message-Id: <20230525081016.1870364-4-thuth@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/rtl8139-test.c

@@ -209,6 +209,10 @@ int main(int argc, char **argv)
 
     g_test_init(&argc, &argv, NULL);
 
+    if (!qtest_has_device("rtl8139")) {
+        return 0;
+    }
+
     qtest_start("-device rtl8139");
 
     qtest_add_func("/rtl8139/nop", nop);