add -fbounds-checking option.
When enabled, clang generates bounds checks for array and pointers dereferences. Work to follow in LLVM's backend.

OK'ed by Chad; thanks for the review.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156431 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index dfb04b4..5d108be 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -41,6 +41,7 @@
     CXXVTTValue(0), OutermostConditional(0), TerminateLandingPad(0),
     TerminateHandler(0), TrapBB(0) {
 
+  BoundsChecking = getContext().getLangOpts().BoundsChecking;
   CatchUndefined = getContext().getLangOpts().CatchUndefined;
   CGM.getCXXABI().getMangleContext().startNewFunction();
 }