Update kernel parts of pppd from 2.2.0 to 2.3.0. I've yet to look at the
2.3.0 -> 2.3.1 changes, but I seem to recall that there are certain
"issues" with 2.3.1 (I'm not sure if it's just pppd or the whole lot, I
am not quite that far). The present pppd seems to work with it just fine
for the time being.
Among the changes are that zlib (aka LZ77 aka deflate aka gzip) compression
is implemented as well as the original compress(1) LZW style.