[clang] [Modules] Detect ODR mismatches for enums in non-C++ like in C++. (PR #90298)

[Volodymyr Sapsai via cfe-commits]

vsapsai wrote:

> C doesn't have an odr, does it?

For non-C++ "ODR" has a meaning more like "ODR-inspired checks". But there is no language rule that would require enforcement and there is no impact on linkage (at least during deserialization).

https://github.com/llvm/llvm-project/pull/90298