IncorrectCguReuseType
In [100753], `IncorrectCguReuseType` accidentally stopped being emitted. Begin emitting it again rather than just blindly dropping it, and adjust tests accordingly. [100753]: 706452eba7 (diff-048389738ddcbe0f9765291a29db1fed9a5f03693d4781cfb5aaa97ffb3c7f84)
706452eba7 (diff-048389738ddcbe0f9765291a29db1fed9a5f03693d4781cfb5aaa97ffb3c7f84)
CGU tests require CGU code to be exercised. We can't merely do "cargo check" on these tests.