Fix bad cut/paste for commit c19e7369

This commit was SVN r32712.

opal/mca/pmix/cray/pmix_cray.c

@@ -257,8 +257,8 @@ static int cray_fini(void) {
     }
 
     if (NULL != pmix_lranks) {
-        pmix_lranks = NULL;
         free(pmix_lranks);
+        pmix_lranks = NULL;
     }
 
     return OPAL_SUCCESS;