Pass --disable-seccomp-filter-sandbox for tests with Qt 5.7.1

This is a stop-gap so I'm able to run end2end tests at least.
See #3163.

For unit tests, we need https://github.com/pytest-dev/pytest-qt/pull/193 first.

tests/end2end/fixtures/quteprocess.py

@@ -33,7 +33,7 @@ import json
 
 import yaml
 import pytest
-from PyQt5.QtCore import pyqtSignal, QUrl
+from PyQt5.QtCore import pyqtSignal, QUrl, qVersion
 
 from qutebrowser.misc import ipc
 from qutebrowser.utils import log, utils, javascript
@@ -422,10 +422,14 @@ class QuteProc(testprocess.Process):
 
     def _default_args(self):
         backend = 'webengine' if self.request.config.webengine else 'webkit'
-        return ['--debug', '--no-err-windows', '--temp-basedir',
+        args = ['--debug', '--no-err-windows', '--temp-basedir',
                 '--json-logging', '--loglevel', 'vdebug',
-                '--backend', backend, '--debug-flag', 'no-sql-history',
-                'about:blank']
+                '--backend', backend, '--debug-flag', 'no-sql-history']
+        if qVersion() == '5.7.1':
+            # https://github.com/qutebrowser/qutebrowser/issues/3163
+            args += ['--qt-flag', 'disable-seccomp-filter-sandbox']
+        args.append('about:blank')
+        return args
 
     def path_to_url(self, path, *, port=None, https=False):
         """Get a URL based on a filename for the localhost webserver.

tests/end2end/test_invocations.py

@@ -27,7 +27,7 @@ import re
 
 import pytest
 
-from PyQt5.QtCore import QProcess
+from PyQt5.QtCore import QProcess, qVersion
 
 
 def _base_args(config):
@@ -37,6 +37,9 @@ def _base_args(config):
         args += ['--backend', 'webengine']
     else:
         args += ['--backend', 'webkit']
+    if qVersion() == '5.7.1':
+        # https://github.com/qutebrowser/qutebrowser/issues/3163
+        args += ['--qt-flag', 'disable-seccomp-filter-sandbox']
     args.append('about:blank')
     return args