Fix build on sr.ht

Hopefully fixing:
```
cc1: warnings being treated as errors
tests/unittests/test_cmd_otr.c: In function
'cmd_otr_start_sends_otr_query_message_to_current_recipeint':
tests/unittests/test_cmd_otr.c:422: warning: 'window.urls_ac' is used
uninitialized in this function
gmake[2]: *** [Makefile:1913: tests/unittests/test_cmd_otr.o] Error 1
gmake[2]: Leaving directory '/home/build/profanity'
gmake[1]: *** [Makefile:2442: check-am] Error 2
gmake[1]: Leaving directory '/home/build/profanity'
gmake: *** [Makefile:2445: check] Error 2
```

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/unittests/test_cmd_otr.c b/tests/unittests/test_cmd_otr.c
index ca55f5b8..f18ca814 100644
--- a/tests/unittests/test_cmd_otr.c
+++ b/tests/unittests/test_cmd_otr.c
@@ -418,6 +418,7 @@ cmd_otr_start_sends_otr_query_message_to_current_recipeint(void **state)
     ProfWin window;
     window.type = WIN_CHAT;
     window.layout = NULL;
+    window.urls_ac = NULL;
     ProfChatWin chatwin;
     chatwin.window = window;
     chatwin.barejid = recipient;