[test][IRGen] Avoid redefinition of bool in huge_c_type.swift
musl and wasi-libc modules contains stdint.h and stdbool.h in their
modulemap, and `#incnlude <stdint.h>` in huge_c_type.h leads including
stdbool.h also in the scope. This results in conflicting the bool
definition, so we should avoid the redefinition.
