[avahi] paths in config.h.in (autoheader)

[Sebastien Estienne]

Hello,

Even if it seems to be a common practice to to use config.h to define
path for socket or pid file, it also seems to be a "bad" practice as i
learnt here:
http://www.delorie.com/gnu/docs/autoconf/autoconf_24.html :
>From this page: 
" A corollary is that you should not use these variables except in
Makefiles. For instance, instead of trying to evaluate datadir in
`configure' and hard-coding it in Makefiles using e.g.,
`AC_DEFINE_UNQUOTED(DATADIR, "$datadir")', you should add
`-DDATADIR="$(datadir)"' to your CPPFLAGS. "

So if noone has objections i'll fix these small problems, following
the autoconf manual recommendations

-- 
Sebastien Estienne