Allow passing args to spawn from :hint.

Instead of creating a new guiprocess manually, just pass the args along
to the spawn command so it can accept args like -v.

Addresses part of #797 by allowing `hint -- all spawn -v echo`.
`hint all spawn -v echo` is still not supported.

qutebrowser/browser/hints.py

@@ -36,7 +36,6 @@ from qutebrowser.keyinput import modeman, modeparsers
 from qutebrowser.browser import webelem
 from qutebrowser.commands import userscripts, cmdexc, cmdutils, runners
 from qutebrowser.utils import usertypes, log, qtutils, message, objreg, utils
-from qutebrowser.misc import guiprocess
 
 
 ElemTuple = collections.namedtuple('ElemTuple', ['elem', 'label'])
@@ -625,9 +624,8 @@ class HintManager(QObject):
         """
         urlstr = url.toString(QUrl.FullyEncoded | QUrl.RemovePassword)
         args = context.get_args(urlstr)
-        cmd, *args = args
-        proc = guiprocess.GUIProcess(self._win_id, what='command', parent=self)
-        proc.start(cmd, args)
+        commandrunner = runners.CommandRunner(self._win_id)
+        commandrunner.run_safely('spawn ' + ' '.join(args))
 
     def _resolve_url(self, elem, baseurl):
         """Resolve a URL and check if we want to keep it.

tests/integration/features/hints.feature

@@ -44,6 +44,12 @@ Feature: Using hints
       And I run :fake-key -g <Esc>
       Then no crash should happen
 
+    Scenario: Using :hint spawn with flags and -- (issue 797)
+        When I open data/hints/link.html
+        And I run :hint -- all spawn -v echo
+        And I run :follow-hint a
+        Then the message "Command exited successfully." should be shown
+
     @xfail
     Scenario: Using :hint spawn with flags (issue 797)
         When I open data/hints/html/simple.html