Mark VD_AGENT_CLIPBOARD_MAX as deprecated
Mark VD_AGENT_CLIPBOARD_MAX as deprecated

There is no use for those 2 values, and the default limit would be quite
wrong.

Put them in a deprecated block. If someone uses them, he will have to
add -DSPICE_DEPRECATED, or just fix the code.

vdiot/spice-protocol,Fantu/spice-protocol,SPICE/spice-protocol,SPICE/spice-protocol,fgouget/spice-protocol,elmarco/spice-protocol,SPICE/spice-protocol,fgouget/spice-protocol,Fantu/spice-protocol,freedesktop-unofficial-mirror/spice__spice-protocol,fgouget/spice-protocol,vdiot/spice-protocol,elmarco/spice-protocol,vdiot/spice-protocol,freedesktop-unofficial-mirror/spice__spice-protocol,elmarco/spice-protocol