ao_wasapi: in exclusive mode do not output multichannel by default

Exactly the same situation as with ao_alsa in commit 0b144eac (except
that we can detect the situation better under wasapi).

Essentially, wasapi will allow us to output any sample format, and not
just the one configured by the user in the audio system settings.

audio/out/ao_wasapi_utils.c

@@ -407,7 +407,7 @@ static bool search_channels(struct ao *ao, WAVEFORMATEXTENSIBLE *wformat)
     }
 
     entry = ao->channels;
-    if (ao_chmap_sel_adjust(ao, &chmap_sel, &entry)){
+    if (ao_chmap_sel_adjust2(ao, &chmap_sel, &entry, !state->opt_exclusive)){
         change_waveformat_channels(wformat, &entry);
         return true;
     }