With BOOL as return type it is not possible to differentiate between
success and "no data can be read" (when a channel read would block).
rdpsnd_server_handle_messages returns now int with the following
possible values:
-1 if no data could be read
0 error (like connection close) (formerly FALSE)
1 succsess (also if further bytes need to be read) (formerly TRUE)
Not using -1 for error cases was chosen to be compatible with the BOOL
return values used before.
MS-RDPEA 2.2.2.3 states (Appendix A <6>) that quality mode PDU
should be ignored if the client version is < 6. For these clients the sound
channel got never activated since activated was only called after
reception of the quality mode PDU.
For clients < version 6 activated is now called after
CLIENT_AUDIO_VERSION_AND_FORMATS was received.
