[clang] [clang][analyzer] Change default value of checker option in unix.StdCLibraryFunctions. (PR #80457)

[Balázs Kéri via cfe-commits]

balazske wrote:

Behavior of `fileno` is already changed in #81842.
I was thinking about that

> separate long-term solution

in last comment that it is already existing functionality (in StreamChecker and other invalid pointer checkers).
Should we run again the checks (only modeling of `fileno` was changed), or is this change acceptable now?

https://github.com/llvm/llvm-project/pull/80457