[libc-commits] [libc] [libc]: Clean up unnecessary function pointers in scanf (PR #121215)

[Michael Jones via libc-commits]

michaelrj-google wrote:

Much appreciated, I'll send you a review once I have something ready. 

Right now it looks like there's two main issues: the `reader` target in `scanf_core` isn't being defined on targets without `FILE`, and once I fix that I run into linker errors with the `reader_test` and some other scanf internals, since link-time dependencies aren't properly propagated through header libraries (defined with `add_header_library` in the cmake).

https://github.com/llvm/llvm-project/pull/121215