Workaround a livelock issue on sparc64

Index: src/hotspot/os/bsd/os_bsd.cpp
--- src/hotspot/os/bsd/os_bsd.cpp.orig
+++ src/hotspot/os/bsd/os_bsd.cpp
@@ -2657,7 +2657,11 @@ bool os::dont_yield() {
 }
 
 void os::naked_yield() {
+#ifndef __OpenBSD__
   sched_yield();
+#else
+  os::naked_short_nanosleep(512);
+#endif
 }
 
 ////////////////////////////////////////////////////////////////////////////////
