Teach utilsOsType about NetBSD

Summary: NetBSD is a free, fast, secure, and highly portable Unix-like Open Source operating system.

Reviewers: joerg, sas

Subscribers: sas, emaste, lldb-commits

Differential Revision: http://reviews.llvm.org/D12615

Change by Kamil Rytarowski <n54@gmx.com>

llvm-svn: 247116