Refactor LTO type determination
Refactor LTO type determination

Instead of only determining whether some form of LTO is necessary,
determine whether thin, fat or no LTO is necessary. I've rewritten
the conditions in a way that I think is more obvious, i.e. specified
LTO type + additional preconditions.

GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,GBGamer/rust