8324678: Replace NULL with nullptr in HotSpot gtests

Reviewed-by: kbarrett, dholmes, jwaters

Author: coleenp

test/hotspot/gtest/compiler/test_directivesParser.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,7 +35,7 @@ class DirectivesParserTest : public ::testing::Test{
   ResourceMark rm;
   stringStream stream;
   // These tests require the "C" locale to correctly parse decimal values
-  DirectivesParserTest() : _locale(setlocale(LC_NUMERIC, NULL)) {
+  DirectivesParserTest() : _locale(setlocale(LC_NUMERIC, nullptr)) {
     setlocale(LC_NUMERIC, "C");
   }
   ~DirectivesParserTest() {

test/hotspot/gtest/gc/g1/test_freeRegionList.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -44,7 +44,7 @@ TEST_VM(FreeRegionList, length) {
 
   // Create a fake heap. It does not need to be valid, as the HeapRegion constructor
   // does not access it.
-  MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords);
+  MemRegion heap(nullptr, num_regions_in_test * HeapRegion::GrainWords);
 
   // Allocate a fake BOT because the HeapRegion constructor initializes
   // the BOT.