Reverse sense of unwind-tables option. This means

stack tracebacks on Darwin x86-64 won't work by default;
nevertheless, everybody but me thinks this is a good idea.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49663 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCRegisterInfo.cpp

@@ -949,7 +949,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineModuleInfo *MMI = MFI->getMachineModuleInfo();
   bool needsFrameMoves = (MMI && MMI->hasDebugInfo()) ||
        !MF.getFunction()->doesNotThrow() ||
-       !UnwindTablesOptional;
+       UnwindTablesMandatory;
   
   // Prepare for frame info.
   unsigned FrameLabelId = 0;