mca/base: fix deprecated variable help message

Actually print out the original variable name.

Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>

opal/mca/base/mca_base_var.c

@@ -11,7 +11,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2008-2015 Cisco Systems, Inc.  All rights reserved.
- * Copyright (c) 2012-2015 Los Alamos National Security, LLC. All rights
+ * Copyright (c) 2012-2017 Los Alamos National Security, LLC. All rights
  *                         reserved.
  * Copyright (c) 2014-2016 Intel, Inc. All rights reserved.
  * Copyright (c) 2015      Research Organization for Information Science
@@ -1640,7 +1640,7 @@ static int var_set_from_env (mca_base_var_t *var, mca_base_var_t *original)
         const char *new_variable = "None (going away)";
 
         if (is_synonym) {
-            new_variable = var->mbv_full_name;
+            new_variable = original->mbv_full_name;
         }
 
         switch (var->mbv_source) {