We must call inflate again in case there's any pending output
despite our input buffer being empty. If the output buffer
is in fact already flushed, inflate() returns Z_BUF_ERROR.
There isn't really an error !
(I *really* meant to do this *before* committing the
deflate changes in the first place - oops).
Pppd is horribly broken in this respect - refer to the
ppp man page for details. Ppp *WON'T* negotiate deflate
with pppd by default - you must ``enable'' and ``accept''
``pppd-deflate'' in your config.
While I'm in there, update the cftypes in ccp.c so that
we recognise some more protocols (we don't actually do
anything with them - just send a REJ).