initialize an instance var, apparently I forgot to commit this long ago

llvm-svn: 25609
diff --git a/llvm/lib/Target/TargetLowering.cpp b/llvm/lib/Target/TargetLowering.cpp
index 1128f74..8f177c9 100644
--- a/llvm/lib/Target/TargetLowering.cpp
+++ b/llvm/lib/Target/TargetLowering.cpp
@@ -32,6 +32,7 @@
   UseUnderscoreSetJmpLongJmp = false;
   IntDivIsCheap = false;
   Pow2DivIsCheap = false;
+  StackPointerRegisterToSaveRestore = 0;
   SchedPreferenceInfo = SchedulingForLatency;
 }