configure.in: only add -lnsl when needed

dpkg-shlibdeps: warning: dependency on libnsl.so.1 [..]
(they use none of its symbols).

As shown via commit 2b14234abc252383679bae2d23861b773dc9713e
(dpkg-shlibdeps: warning: dependency on libnsl.so.1) and the
following revert of that commit, we cannot simply drop
the AC_CHECK_LIB(nsl). Although -lnsl is indeed unneeded
when glibc is used, some platforms (e.g. Solaris) need it.

Use AC_SEARCH_LIBS instead to only link when the library exports
a particular symbol.

diff --git a/configure.in b/configure.in
index 10a72d35a0ffa8a2666f0f4860bb8356c93ccb84..f80e8a96595e5b124553e1b8442d10d66bfb36ef 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -131,9 +131,11 @@ AC_CHECK_MEMBER([struct sockaddr_in.sin_len], AC_DEFINE(HAVE_sockaddr_in_len),,
 
 # -- Libraries --
 
+# A/UX needs this.
 AC_CHECK_LIB(UTIL,memmove)
+# needed on solaris. GNU libc also has a libnsl, but we do not need it.
+AC_SEARCH_LIBS(gethostbyname,nsl)
 AC_CHECK_LIB(socket,bind)
-AC_CHECK_LIB(nsl,gethostent)
 
 # -- Functions --