I don't think this is worth fixing. Typedef redefinitions are a C11 feature, and Wine already requires the compiler to support other C11 features like anonymous unions and designated initializers. I would prefer to just document that Wine requires the compiler to support C11 and not attempt to support any compiler that falls short.
We don't compile code with a C standard, we compile it with the actual compilers that people have on their machine, none of which are 100% standards-compliant.
If actual users are running into a problem, we want to make an effort to fix it. If the fix turns out to be too complicated or ugly, we may decide not to implement it, but we should never refuse to support users just because of what some C standard says.