Introduce libosmo-ranap.so as shared RANAP lib

This shared RANAP library will be used not only by hnbgw, but also by
OsmoCSCN, OsmoSGSN.
diff --git a/configure.ac b/configure.ac
index 018aa17..dd5e24f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,6 +2,8 @@
 dnl	m4_esyscmd([./git-version-gen .tarball-version]),
 	[openbsc@lists.osmocom.org])
 
+LT_INIT
+
 AM_INIT_AUTOMAKE([foreign dist-bzip2 no-dist-gzip 1.6 subdir-objects])
 AC_CONFIG_TESTDIR(src/tests)
 
@@ -13,7 +15,6 @@
 AC_PROG_MKDIR_P
 AC_PROG_CC
 AC_PROG_INSTALL
-AC_PROG_RANLIB
 
 PKG_CHECK_MODULES(OSMOCORE, libosmocore)
 PKG_CHECK_MODULES(OSMOGSM, libosmogsm)