Fix UB in test helpers
Fix UB in test helpers

Macro expansion producing defined has undefined behavior in C/C++.

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