[C++11] Use 'nullptr'.

llvm-svn: 210442
diff --git a/llvm/utils/FileCheck/FileCheck.cpp b/llvm/utils/FileCheck/FileCheck.cpp
index a124377..74c7082 100644
--- a/llvm/utils/FileCheck/FileCheck.cpp
+++ b/llvm/utils/FileCheck/FileCheck.cpp
@@ -1043,7 +1043,7 @@
              SMLoc::getFromPointer(Buffer.data())))->getBufferStart() &&
          "CHECK-NEXT can't be the first check in a file");
 
-  const char *FirstNewLine = 0;
+  const char *FirstNewLine = nullptr;
   unsigned NumNewLines = CountNumNewlinesBetween(Buffer, FirstNewLine);
 
   if (NumNewLines == 0) {