Reuse sanitizer_linux for NetBSD

Summary:
Follow FreeBSD and reuse sanitizer_linux for NetBSD.

Part of the code inspired by the original work on libsanitizer in GCC 5.4 by Christos Zoulas.

Sponsored by <The NetBSD Foundation>

Reviewers: joerg, kcc, filcab, vitalybuka, fjricci, dvyukov

Reviewed By: fjricci

Subscribers: dvyukov, emaste, kubamracek, llvm-commits, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D36325

llvm-svn: 310411