Reapply "[clang][analyzer] StreamChecker: Model getc, vfscanf, putc, vfprintf" (#83281)

`va_list` is a platform-specific type. On some, it is a struct instead
of a pointer to a struct, so `lookupFn` was ignoring calls to `vfprintf`
and `vfscanf`.

`stream.c` now runs in four different platforms to make sure the logic
works across targets.