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.
(we overwrite the password and pin arguments).
This implies changes in the argument parsing tests that now must pass a mutable argv
(copied from the statically declared test argvs).
Some other const inconsistency have been dealt with too.
The sound and microphone redirection channels (and in part TSMF)
did not properly decouple encoding/decoding from the backends used
to play/record sound.
Encapsulating encoding/decoding in rewritten freerdp_dsp_* functions
with variable backends, simplifying alsa/oss/pulse/... audio backends.
