Skip test_ipc:test_timeout on OS X.

It almost always causes issues and I have no idea why... Let's skip it for now.

Fixes #975.

tests/unit/misc/test_ipc.py

@@ -592,6 +592,8 @@ class TestSendToRunningInstance:
         assert str(excinfo.value) == msg
 
 
+@pytest.mark.not_osx(reason="https://github.com/The-Compiler/qutebrowser/"
+                            "issues/975")
 def test_timeout(qtbot, caplog, qlocalsocket, ipc_server):
     ipc_server._timer.setInterval(100)
     ipc_server.listen()