[clang-tidy] new check: bugprone-posix-return

Summary:
Checks if any calls to posix functions (except posix_openpt) expect negative return values.
These functions return either 0 on success or an errno on failure, which is positive only.

Reviewers: JonasToth, gribozavr, alexfh, hokein

Reviewed By: gribozavr

Subscribers: Eugene.Zelenko, lebedev.ri, llozano, george.burgess.iv, xazax.hun, srhines, mgorny, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63623

Patch by Jian Cai.

llvm-svn: 365007