This PR fixes the handling of using rdpsnd or audin when the system has
no audio device available.
In case of a missing playback device the
Windows backend now correctly reports an error and the fake rdpsnd
backend is loaded.
If audin is enabled and no microphone is present the channel
initialization will report an error but it won't cut the connection (as
it did before).
[client/X11/xf_floatbar.c:800] -> [client/X11/xf_floatbar.c:796]: (warning) Either the condition '!floatbar' is redundant or there is possible null pointer dereference: floatbar.
[client/X11/xf_floatbar.c:800] -> [client/X11/xf_floatbar.c:797]: (warning) Either the condition '!floatbar' is redundant or there is possible null pointer dereference: floatbar.
[client/X11/xf_floatbar.c:800] -> [client/X11/xf_floatbar.c:798]: (warning) Either the condition '!floatbar' is redundant or there is possible null pointer dereference: floatbar.
[libfreerdp/codec/dsp.c:1156] -> [libfreerdp/codec/dsp.c:1154]: (warning) Either the condition '!srcFormat' is redundant or there is possible null pointer dereference: srcFormat.
[channels/drdynvc/client/drdynvc_main.c:1453] -> [channels/drdynvc/client/drdynvc_main.c:1450]: (warning) Either the condition '!drdynvc' is redundant or there is possible null pointer dereference: drdynvc.
[channels/audin/client/opensles/audin_opensl_es.c:98] -> [channels/audin/client/opensles/audin_opensl_es.c:94]: (warning) Either the condition '!opensles' is redundant or there is possible null pointer dereference: opensles.
[channels/audin/client/opensles/audin_opensl_es.c:159] -> [channels/audin/client/opensles/audin_opensl_es.c:153]: (warning) Either the condition '!opensles' is redundant or there is possible null pointer dereference: opensles.
