Add OpenBSD support to be able to get the thread name

llvm-svn: 353367
diff --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
index c87a166..767f626 100644
--- a/llvm/lib/Support/Unix/Threading.inc
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -202,6 +202,12 @@
   ::pthread_getname_np(::pthread_self(), buf, len);
 
   Name.append(buf, buf + strlen(buf));
+#elif defined(__OpenBSD__)
+  constexpr uint32_t len = get_max_thread_name_length_impl();
+  char buf[len];
+  ::pthread_get_name_np(::pthread_self(), buf, len);
+
+  Name.append(buf, buf + strlen(buf));
 #elif defined(__linux__)
 #if HAVE_PTHREAD_GETNAME_NP
   constexpr uint32_t len = get_max_thread_name_length_impl();