Rename `OUTBOUND_ADDR_EXIT_AND_OR` to `OUTBOUND_ADDR_ANY`.

This patch renames the enumeration value in `outbound_addr_t` from
`OUTBOUND_ADDR_EXIT_AND_OR` to `OUTBOUND_ADDR_ANY` since with the
arrival of `OUTBOUND_ADDR_PT` it no longer makes sense to call the
fallback value for "Exit and OR". Instead we rename it to "any".

See: https://bugs.torproject.org/5304