[Analyzer][StreamChecker] Added check for "indeterminate file position".

Summary:
According to the standard, after a `wread` or `fwrite` call the file position
becomes "indeterminate". It is assumable that a next read or write causes
undefined behavior, so a (fatal error) warning is added for this case.
The indeterminate position can be cleared by some operations, for example
`fseek` or `freopen`, not with `clearerr`.

Reviewers: Szelethus, baloghadamsoftware, martong, NoQ, xazax.hun, dcoughlin

Reviewed By: Szelethus

Subscribers: rnkovacs, NoQ, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, gamesh411, Charusso, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80018