IWYU: Add missing cstddef includes for size_t and nullptr_t

The IWYU tool we use for CI now diagnoses these.

Source/CPack/IFW/cmCPackIFWCommon.cxx

@@ -11,6 +11,7 @@
 #include "cmVersionConfig.h"
 #include "cmXMLWriter.h"
 
+#include <cstddef>
 #include <sstream>
 #include <utility>
 #include <vector>

Source/CTest/cmCTestTestHandler.cxx

@@ -28,6 +28,7 @@
 #include <cmsys/Base64.h>
 #include <cmsys/Directory.hxx>
 #include <cmsys/RegularExpression.hxx>
+#include <cstddef>
 #include <cstring>
 #include <functional>
 #include <iomanip>

Source/cmFileAPI.cxx

@@ -17,6 +17,7 @@
 #include <algorithm>
 #include <cassert>
 #include <chrono>
+#include <cstddef>
 #include <ctime>
 #include <iomanip>
 #include <sstream>

Source/cmGeneratorTarget.cxx

@@ -5,6 +5,7 @@
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
 #include <assert.h>
+#include <cstddef>
 #include <errno.h>
 #include <iterator>
 #include <memory>

Source/cmListCommand.cxx

@@ -5,6 +5,7 @@
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
 #include <assert.h>
+#include <cstddef>
 #include <functional>
 #include <iterator>
 #include <set>

Source/cmProjectCommand.cxx

@@ -4,6 +4,7 @@
 
 #include "cmsys/RegularExpression.hxx"
 #include <array>
+#include <cstddef>
 #include <cstdio>
 #include <functional>
 #include <limits>

Source/cmQtAutoGenInitializer.cxx

@@ -29,6 +29,7 @@
 #include "cmsys/SystemInformation.hxx"
 
 #include <algorithm>
+#include <cstddef>
 #include <deque>
 #include <initializer_list>
 #include <map>

Source/cmString.hxx

@@ -9,6 +9,7 @@
 #include "cm_string_view.hxx"
 
 #include <algorithm>
+#include <cstddef>
 #include <functional>
 #include <initializer_list>
 #include <memory>

Source/cmStringAlgorithms.cxx

@@ -3,6 +3,7 @@
 #include "cmStringAlgorithms.h"
 
 #include <algorithm>
+#include <cstddef>
 #include <cstdio>
 #include <errno.h>
 #include <stdlib.h>

Source/cmUVProcessChain.h

@@ -6,6 +6,7 @@
 #include "cm_uv.h"
 
 #include <array>
+#include <cstddef>
 #include <iosfwd>
 #include <memory>
 #include <string>

Source/cmXMLWriter.h

@@ -8,6 +8,7 @@
 #include "cmXMLSafe.h"
 
 #include <chrono>
+#include <cstddef>
 #include <ctime>
 #include <ostream>
 #include <stack>

Tests/CMakeLib/testString.cxx

@@ -6,6 +6,7 @@
 #include "cm_static_string_view.hxx"
 #include "cm_string_view.hxx"
 
+#include <cstddef>
 #include <cstring>
 #include <iostream>
 #include <iterator>