Specifying sysconfdir file path in config.h with autoconf?

[Qaxi]

Hi
I want to have a configuration file in the sysconfdir for my program,
but if
I put AC_DEFINE_UNQUOTED(CONFFILE, "$sysconfdir/file.conf"), I end up
with
the path being "${prefix}/etc/file.conf" which is pretty meaningless to
C.
I've seen people hack it by just saying "$prefix/etc/file.conf" in the
configure.in, but this doesn't seem to be the right thing to do.
Should I
do that, or is there a way to use the sysconfdir?

Petr klima