Link sanitized programs on NetBSD with -lkvm

[krytarowski]

Summary

kvm - kernel memory interface

The kvm(3) functions like kvm_open(), kvm_getargv() or kvm_getenvv()
are used in programs that can request information about a kernel and
its processes. The LLVM sanitizers will make use of them on NetBSD.

Sponsored by <The NetBSD Foundation>

[vitalybuka]

Please update the summary. No need to define kvm. Probably just few example of essential functions needed by sanitizers.

[vitalybuka]

LGTM, but please update the summary and git/svn patch description

lib/Driver/ToolChains/CommonArgs.cpp

if (TC.getTriple().getOS() != llvm::Triple::FreeBSD &&
       TC.getTriple().getOS() != llvm::Triple::RTEMS)
     CmdArgs.push_back("-ldl");
   // Required for forkpty on some OSes
   if (TC.getTriple().getOS() == llvm::Triple::NetBSD)
     CmdArgs.push_back("-lutil");
   // Required for backtrace on some OSes
   if (TC.getTriple().getOS() == llvm::Triple::NetBSD)
     CmdArgs.push_back("-lexecinfo");
+  // Required for kvm (kernel memory interface) on some OSes
+  if (TC.getTriple().getOS() == llvm::Triple::NetBSD)
+    CmdArgs.push_back("-lkvm");
 }
 
 static void
 collectSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
                          SmallVectorImpl<StringRef> &SharedRuntimes,
                          SmallVectorImpl<StringRef> &StaticRuntimes,
                          SmallVectorImpl<StringRef> &NonWholeStaticRuntimes,
                          SmallVectorImpl<StringRef> &HelperStaticRuntimes,