[Analyzer][StreamChecker] Added check for "indeterminate file position".
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
Differential Revision: https://reviews.llvm.org/D80018