message: Implement __kmp_gettid() for NetBSD
  Summary: _lwp_self() returns current Thread Id in a numeric version on NetBSD.
  Reviewers: joerg, mgorny, #openmp
  Subscribers: llvm-commits, openmp-commits, #openmp
  Tags: #openmp
diff: #if KMP_OS_DARWIN
  // OS X
  #define __kmp_gettid() syscall(SYS_thread_selfid)
  +#elif KMP_OS_NETBSD
  +#include <lwp.h>
  +#define __kmp_gettid() _lwp_self()
  #elif defined(SYS_gettid)
  // Hopefully other Unix systems define SYS_gettid syscall for getting os thread
  // id
  