Add NetBSD support in Host::GetCurrentThreadID

[krytarowski]

Summary

To retrieve the native thread ID there must be called _lwp_self().

Sponsored by <The NetBSD Foundation>

source/Host/common/Host.cpp

 #include <sys/syscall.h>
 #include <sys/wait.h>
 #endif
 
 #if defined(__FreeBSD__)
 #include <pthread_np.h>
 #endif
 
+#if defined(__NetBSD__)
+#include <lwp.h>
+#endif
+
 // C++ Includes
 
 // Other libraries and framework includes
 // Project includes
 
 #include "lldb/Core/ArchSpec.h"
 #include "lldb/Core/Error.h"
 #include "lldb/Core/Log.h"
#if defined(__APPLE__)
   // Calling "mach_thread_self()" bumps the reference count on the thread
   // port, so we need to deallocate it. mach_task_self() doesn't bump the ref
   // count.
   thread_port_t thread_self = mach_thread_self();
   mach_port_deallocate(mach_task_self(), thread_self);
   return thread_self;
 #elif defined(__FreeBSD__)
   return lldb::tid_t(pthread_getthreadid_np());
+#elif defined(__NetBSD__)
+  return lldb::tid_t(_lwp_self());
 #elif defined(__ANDROID__)
   return lldb::tid_t(gettid());
 #elif defined(__linux__)
   return lldb::tid_t(syscall(SYS_gettid));
 #else
   return lldb::tid_t(pthread_self());
 #endif
 }