tests/qtest/fuzz-test: Quit test_lp1878642 once done

Missed in fd25017 ("qtest: add a reproducer for LP#1878642").

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201201191026.4149955-2-philmd@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/fuzz-test.c

@@ -45,6 +45,7 @@ static void test_lp1878642_pci_bus_get_irq_level_assert(void)
     qtest_outl(s, 0xcf8, 0x8400f841);
     qtest_outl(s, 0xcfc, 0xebed205d);
     qtest_outl(s, 0x5d02, 0xebed205d);
+    qtest_quit(s);
 }
 
 int main(int argc, char **argv)