Use nullptr instead of NULL for variadic sentinels

Windows defines NULL to 0, which when used as an argument to a variadic
function, is not a null pointer constant. As a result, Clang's
-Wsentinel fires on this code. Using '0' would be wrong on most 64-bit
platforms, but both MSVC and Clang make it work on Windows. Sidestep the
issue with nullptr.

llvm-svn: 221940
diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 2f33ee8..dcdcfa1 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -134,11 +134,11 @@
   appendToGlobalCtors(M, CtorFunc, kSanCtorAndDtorPriority);
 
   SanCovFunction =
-      checkInterfaceFunction(M.getOrInsertFunction(kSanCovName, VoidTy, NULL));
+      checkInterfaceFunction(M.getOrInsertFunction(kSanCovName, VoidTy, nullptr));
   SanCovIndirCallFunction = checkInterfaceFunction(M.getOrInsertFunction(
-      kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, NULL));
+      kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
   SanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
-      kSanCovModuleInitName, Type::getVoidTy(*C), IntptrTy, NULL));
+      kSanCovModuleInitName, Type::getVoidTy(*C), IntptrTy, nullptr));
   SanCovModuleInit->setLinkage(Function::ExternalLinkage);
 
   for (auto &F : M)