[C++] Use 'nullptr'. Target edition.

llvm-svn: 207197
diff --git a/llvm/lib/Target/X86/X86PadShortFunction.cpp b/llvm/lib/Target/X86/X86PadShortFunction.cpp
index 76b318e..84521cc 100644
--- a/llvm/lib/Target/X86/X86PadShortFunction.cpp
+++ b/llvm/lib/Target/X86/X86PadShortFunction.cpp
@@ -50,7 +50,7 @@
   struct PadShortFunc : public MachineFunctionPass {
     static char ID;
     PadShortFunc() : MachineFunctionPass(ID)
-                   , Threshold(4), TM(0), TII(0) {}
+                   , Threshold(4), TM(nullptr), TII(nullptr) {}
 
     bool runOnMachineFunction(MachineFunction &MF) override;