btl/sm: rename file after file descriptor has been closed.

Thanks George for spotting this.

opal/mca/btl/sm/btl_sm_component.c

@@ -696,6 +696,8 @@ create_rndv_file(mca_btl_sm_component_t *comp_ptr,
         /* only do this for the mpool case */
         OBJ_RELEASE(tmp_modp);
     }
+    (void)close(fd);
+    fd = -1;
     if (0 != rename(tmpfname, fname)) {
         rc = OPAL_ERR_IN_ERRNO;
         goto out;