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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207196 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/BypassSlowDivision.cpp

@@ -54,11 +54,11 @@ namespace llvm {
     }
 
     static DivOpInfo getEmptyKey() {
-      return DivOpInfo(false, 0, 0);
+      return DivOpInfo(false, nullptr, nullptr);
     }
 
     static DivOpInfo getTombstoneKey() {
-      return DivOpInfo(true, 0, 0);
+      return DivOpInfo(true, nullptr, nullptr);
     }
 
     static unsigned getHashValue(const DivOpInfo &Val) {