AC_SUBST(SMCLIENT_CFLAGS)
AC_SUBST(SMCLIENT_LIBS)
-BACKEND_LIBTOOL_FLAGS="-module -avoid-version -export-symbols \$(top_srcdir)/backend/backend.symbols"
+BACKEND_LIBTOOL_FLAGS="-module -avoid-version -no-undefined -export-symbols \$(top_srcdir)/backend/backend.symbols"
AC_SUBST(BACKEND_LIBTOOL_FLAGS)
dnl ===== Check special functions