Update LLVM for rebase to r212749.

Includes a cherry-pick of:
r212948 - fixes a small issue with atomic calls

Change-Id: Ib97bd980b59f18142a69506400911a6009d9df18
diff --git a/lib/CodeGen/LiveDebugVariables.h b/lib/CodeGen/LiveDebugVariables.h
index bb67435..7ec0d17 100644
--- a/lib/CodeGen/LiveDebugVariables.h
+++ b/lib/CodeGen/LiveDebugVariables.h
@@ -22,6 +22,7 @@
 #define LLVM_CODEGEN_LIVEDEBUGVARIABLES_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 
 namespace llvm {
@@ -32,6 +33,7 @@
 
 class LiveDebugVariables : public MachineFunctionPass {
   void *pImpl;
+  DenseMap<const Function*, DISubprogram> FunctionDIs;
 public:
   static char ID; // Pass identification, replacement for typeid
 
@@ -64,6 +66,7 @@
   bool runOnMachineFunction(MachineFunction &) override;
   void releaseMemory() override;
   void getAnalysisUsage(AnalysisUsage &) const override;
+  bool doInitialization(Module &) override;
 
 };