Disable the Load Stack Guard for OpenBSD on AArch64.  We don't use it
on any other platform and it causes a segfault in combination with our
IR Stack Guard.

Index: lib/Target/AArch64/AArch64ISelLowering.cpp
--- lib/Target/AArch64/AArch64ISelLowering.cpp.orig
+++ lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -17364,7 +17364,8 @@ void AArch64TargetLowering::ReplaceNodeResults(
 }
 
 bool AArch64TargetLowering::useLoadStackGuardNode() const {
-  if (Subtarget->isTargetAndroid() || Subtarget->isTargetFuchsia())
+  if (Subtarget->isTargetAndroid() || Subtarget->isTargetFuchsia() ||
+      Subtarget->isTargetOpenBSD())
     return TargetLowering::useLoadStackGuardNode();
   return true;
 }