[clang] [clang][analyzer] Fix StreamChecker `ftell` and `fgetpos` at indeterminate file position. (PR #84191)

[Balazs Benics via cfe-commits]

https://github.com/steakhal approved this pull request.

I haven't gone deep into this PR, but it looks good to me.
Please wait for someone else to sign it too.

https://github.com/llvm/llvm-project/pull/84191