Add libtool support.

libzebra and libospfapiclient are now built shared, and linked shared
with the daemons.  This reduces the memory needed when running
multiple daemons; each daemon is at least 150k smaller.  Static
libraries are still built, and libtool should use them on platforms
which don't have shared libaries.  As with autoconf, the user of a
distribution does not need libtool; one just needs that to build from
CVS.

libospf.a is still a non-shared library, and still installed, not
because that makese sense, but because I don't understand why it is
the way it is now.

Note that the tree was tagged 'libtool-before' just before this commit.
diff --git a/configure.ac b/configure.ac
index bd6b4ff..632de2a 100755
--- a/configure.ac
+++ b/configure.ac
@@ -5,7 +5,7 @@
 ##  Copyright (c) 1996, 97, 98, 99, 2000 Kunihiro Ishiguro <kunihiro@zebra.org>
 ##  Portions Copyright (c) 2003 Paul Jakma <paul@dishone.st>
 ##
-## $Id: configure.ac,v 1.54 2004/06/30 14:25:12 gdt Exp $
+## $Id: configure.ac,v 1.55 2004/06/30 17:36:11 gdt Exp $
 AC_PREREQ(2.53)
 
 AC_INIT(quagga, 0.96.5, [http://bugzilla.quagga.net])
@@ -64,6 +64,11 @@
 dnl ---------
 AC_AIX
 
+dnl -------
+dnl libtool
+dnl -------
+AM_PROG_LIBTOOL
+
 dnl ----------------------
 dnl Packages configuration
 dnl ----------------------