experimental DNS fingerprint

[Damien Miller]

Roumen Petrov wrote:
> Please find attached file "configure.ac+dns.patch".
> This patch allow to compile current (30 Jun 2003) with options 
> --with-dns on my platform.

Applied - thanks.

> AC_SEARCH_LIBS(res_query, resolv)

hmm, there are probably a few places in configure.ac where we should use
AC_SEARCH_LIBS rather than AC_CHECK_LIB.

AC_CHECK_LIB seems to insert duplicate libraries on matching,
AC_SEARCH_LIBS is smarter.

-d