Add NetBSD support in tsan_interceptors.cc

Summary:
NetBSD is a POSIX-like BSD Operating System.

Sponsored by <The NetBSD Foundation>

Reviewers: joerg, kcc, vitalybuka, dvyukov, eugenis

Reviewed By: dvyukov

Subscribers: srhines, kubamracek, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D37305

llvm-svn: 312160