[clang] Diagnose problematic uses of constructor/destructor attribute (PR #67673)

[Fangrui Song via cfe-commits]

MaskRay wrote:

(Was out of town...)

As mentioned at https://github.com/llvm/llvm-project/pull/67360#issuecomment-1736187374 , I think a default error is probably not appropriate. A priority value <= 100 may compete with a runtime `__attribute__((constructor(X)))` but more often it will work. A warning is fine.

https://github.com/llvm/llvm-project/pull/67673