[clang][analyzer] Extend StreamChecker with some new functions.

The stream handling functions `ftell`, `rewind`, `fgetpos`, `fsetpos`
are evaluated in the checker more exactly than before.
New tests are added to test behavior of the checker together with
StdLibraryFunctionsChecker. The option ModelPOSIX of that checker
affects if (most of) the stream functions are recognized, and checker
StdLibraryFunctionArgs generates warnings if constraints for arguments
are not satisfied. The state of `errno` is set by StdLibraryFunctionsChecker
too for every case in the stream functions.
StreamChecker works with the stream state only, does not set the errno state,
and is not dependent on other checkers.

Reviewed By: Szelethus

Differential Revision: https://reviews.llvm.org/D140395