TODO: Split out pg_resetxlog output into pre- and post-sections

https://commitfest.postgresql.org/action/patch_view?id=1281
http://archives.postgresql.org/message-id/CAA4eK1+DxWVtLbapzsg4NEwzQ3dMrB-oNy6mbsbiBEusyQEiJg@mail.gmail.com