configury: do not use libnl-3 when it is half broken

Refs. open-mpi/ompi#4211

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

config/opal_check_libnl.m4

@@ -1,6 +1,6 @@
 dnl -*- shell-script -*-
 dnl
-dnl Copyright (c) 2015-2016 Research Organization for Information Science
+dnl Copyright (c) 2015-2017 Research Organization for Information Science
 dnl                         and Technology (RIST). All rights reserved.
 dnl $COPYRIGHT$
 dnl
@@ -217,7 +217,8 @@ AC_DEFUN([OPAL_CHECK_LIBNL_V3],[
     # If we found everything
     AS_IF([test $opal_libnlv3_happy -eq 1],
           [$2_LIBS="-lnl-3 -lnl-route-3"
-           OPAL_HAVE_LIBNL3=1])
+           OPAL_HAVE_LIBNL3=1],
+          [$2_LIBS=""])
 
    OPAL_VAR_SCOPE_POP
 ])