Ensure to only finalize if we did a selection

This commit was SVN r615.

src/mca/mpi/pml/base/pml_base_close.c

@@ -15,13 +15,13 @@
 
 int mca_pml_base_close(void)
 {
-  extern lam_list_t mca_pml_base_modules_available;
-
   /* Blatently ignore the return code (what would we do to recover,
      anyway?  This module is going away, so errors don't matter
      anymore) */
 
-  mca_pml.pml_finalize();
+  if (NULL != mca_pml.pml_finalize) {
+    mca_pml.pml_finalize();
+  }
 
   /* Close all remaining available modules (may be one if this is a
      LAM RTE program, or [possibly] multiple if this is laminfo) */

src/mca/mpi/pml/base/pml_base_open.c

@@ -44,6 +44,11 @@ int mca_pml_base_open(void)
     return LAM_ERROR;
   }
 
+  /* Set a sentinel in case we don't select any modules (e.g.,
+     laminfo) */
+
+  mca_pml.pml_finalize = NULL;
+
   /* All done */
 
   return LAM_SUCCESS;