Switch order on GhcMake.IsBoot

In !1798 (closed) we were requested to replace many Bools with this data type. But those bools had False meaning NotBoot, so the Ord instance would be flipped if we use this data-type as-is.

Since the planned formally-Bool occurrences vastly outnumber the current occurrences, we figured it would be better to conform the Ord instance to how the Bool is used now, fixing any issues, rather than fix them currently with the bigger refactor later in !1798 (closed). That way, !1798 (closed) can be a "pure" refactor with no behavioral changes.