[clang] [analyzer] Note last "fclose" call from "ensureStreamOpened" (PR #109112)

[Donát Nagy via cfe-commits]

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

I like this improvement :smile:, thanks for implementing it!

The code that you added LGTM, my only concern is the awkward warning message which was inherited from the earlier state of the codebase. I think it would be nice to slip in an "attack of opportunity" that improves it, but I can also change that message in a follow-up commit if you don't want to bother with it. 

https://github.com/llvm/llvm-project/pull/109112