btl/openib: disable XRC by default

Change the default enable configure option XRC to disabled.  If a user want's
to give it a try they have to explicitly ask for it.

Modify the configury help message to indicate it is not enabled by default.

Related to #3890
Fixes #3969

Signed-off-by: Howard Pritchard <howardp@lanl.gov>

NEWS

@@ -12,7 +12,7 @@ Copyright (c) 2006-2017 Cisco Systems, Inc.  All rights reserved.
 Copyright (c) 2006      Voltaire, Inc. All rights reserved.
 Copyright (c) 2006      Sun Microsystems, Inc.  All rights reserved.
                         Use is subject to license terms.
-Copyright (c) 2006-2016 Los Alamos National Security, LLC.  All rights
+Copyright (c) 2006-2017 Los Alamos National Security, LLC.  All rights
                         reserved.
 Copyright (c) 2010-2012 IBM Corporation.  All rights reserved.
 Copyright (c) 2012      Oak Ridge National Labs.  All rights reserved.
@@ -70,6 +70,7 @@ Master (not on release branches yet)
   orte daemon, rather than the mpirun process.   This may be useful to set to
   true when using SLURM, as it improves interoperability with SLURM's signal
   propagation tools.  By default it is set to false, except for Cray XC systems.
+- Remove IB XRC support from the OpenIB BTL due to lack of support.
 
 3.0.0 -- July, 2017
 -------------------

config/opal_check_openfabrics.m4

@@ -11,7 +11,7 @@
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
 # Copyright (c) 2006-2016 Cisco Systems, Inc.  All rights reserved.
-# Copyright (c) 2006-2016 Los Alamos National Security, LLC.  All rights
+# Copyright (c) 2006-2017 Los Alamos National Security, LLC.  All rights
 #                         reserved.
 # Copyright (c) 2006-2009 Mellanox Technologies. All rights reserved.
 # Copyright (c) 2010-2012 Oracle and/or its affiliates.  All rights reserved.
@@ -301,12 +301,13 @@ AC_DEFUN([OPAL_CHECK_OPENFABRICS],[
 
 AC_DEFUN([OPAL_CHECK_OPENFABRICS_CM_ARGS],[
     #
-    # ConnectX XRC support
+    # ConnectX XRC support - disabled see issue #3890
     #
-    AC_ARG_ENABLE([openib-connectx-xrc],
-        [AC_HELP_STRING([--enable-openib-connectx-xrc],
-                        [Enable ConnectX XRC support in the openib BTL. If you do not have InfiniBand ConnectX adapters, you may disable the ConnectX XRC support. If you do not know which InfiniBand adapter is installed on your cluster, leave this option enabled (default: enabled)])],
-                        [enable_connectx_xrc="$enableval"], [enable_connectx_xrc="yes"])
+dnl    AC_ARG_ENABLE([openib-connectx-xrc],
+dnl        [AC_HELP_STRING([--enable-openib-connectx-xrc],
+dnl                        [Enable ConnectX XRC support in the openib BTL. (default: disabled)])],
+dnl                        [enable_connectx_xrc="$enableval"], [enable_connectx_xrc="no"])
+    enable_connectx_xrc="no"
     #
     # Unconnect Datagram (UD) based connection manager
     #