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

llvm-svn: 207176
diff --git a/llvm/tools/llvm-profdata/llvm-profdata.cpp b/llvm/tools/llvm-profdata/llvm-profdata.cpp
index 3e58bc2..17710f6 100644
--- a/llvm/tools/llvm-profdata/llvm-profdata.cpp
+++ b/llvm/tools/llvm-profdata/llvm-profdata.cpp
@@ -156,7 +156,7 @@
 
   StringRef ProgName(sys::path::filename(argv[0]));
   if (argc > 1) {
-    int (*func)(int, const char *[]) = 0;
+    int (*func)(int, const char *[]) = nullptr;
 
     if (strcmp(argv[1], "merge") == 0)
       func = merge_main;