remove unused parameters from:
        EqzFilter() (equalizer.c)
        stereo_to_mono(), mono(), stereo2mono_downmix() (channel_mixer/mono.c)

rc.c: disable update code

    Transform(): remove unused parameter
    avoids useless unused parameter warnings

(You really don't usually want your net_Read/net_Write to interrupted).
In the process, fix a deadlock in vlc_cond_wait() when waitpipe is used - fixes #1448

    mvar_InfoSetNew(): removes unused parameter
    avoids unused parameter warnings from httpd callbacks

network/udp.c net_SetCSCov(): removes warnings if UDPLITE_RECV_CSCOV and DCCP_SOCKOPT_SEND_CSCOV are not defined