OSS player: convert device name to UTF-8 string.

Originally committed to SVN as r4071.

aegisub/src/audio_player_oss.cpp

@@ -82,7 +82,7 @@ void OSSPlayer::OpenStream()
 
     // Open device
     wxString device = Options.AsText(_T("Audio OSS Device"));
-    dspdev = ::open(device, O_WRONLY, 0);
+    dspdev = ::open(device.mb_str(wxConvUTF8), O_WRONLY, 0);
     if (dspdev < 0) {
         throw _T("OSS player: opening device failed");
     }