Fix nulltpr typo in comment. NFC

The patch fixes the typo "nulltpr", accidentally found in comments.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D122993

llvm/include/llvm/Target/TargetLoweringObjectFile.h

@@ -277,7 +277,7 @@ public:
   }
 
   /// If supported, return the function entry point symbol.
-  /// Otherwise, returns nulltpr.
+  /// Otherwise, returns nullptr.
   /// Func must be a function or an alias which has a function as base object.
   virtual MCSymbol *getFunctionEntryPointSymbol(const GlobalValue *Func,
                                                 const TargetMachine &TM) const {

llvm/lib/MC/MCWin64EH.cpp

@@ -514,7 +514,7 @@ static void ARM64EmitUnwindCode(MCStreamer &streamer, const MCSymbol *begin,
 }
 
 // Returns the epilog symbol of an epilog with the exact same unwind code
-// sequence, if it exists.  Otherwise, returns nulltpr.
+// sequence, if it exists.  Otherwise, returns nullptr.
 // EpilogInstrs - Unwind codes for the current epilog.
 // Epilogs - Epilogs that potentialy match the current epilog.
 static MCSymbol*