replace stddef.h with cstddef

The former is deprecated with C++14. The standard says both are the same:

The contents and meaning of the header<cstddef>are the same as the C
standard library header<stddef.h>,except that it does not declare the type
wchar_t, that it also declares the type byte and its associated
operations (21.2.5), and as noted in 21.2.3 and 21.2.4.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/util/Alloc.hxx

@@ -22,7 +22,7 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * Allocate memory.  Use free() to free it.

src/util/ByteReverse.hxx

@@ -20,8 +20,9 @@
 #ifndef MPD_BYTE_REVERSE_HXX
 #define MPD_BYTE_REVERSE_HXX
 
+#include <cstddef>
+
 #include <stdint.h>
-#include <stddef.h>
 
 /**
  * Reverse the bytes in each 16 bit "frame".  This function can be

src/util/Cast.hxx

@@ -33,7 +33,7 @@
 #include "OffsetPointer.hxx"
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 template<typename T, typename U>
 constexpr T *

src/util/CircularBuffer.hxx

@@ -33,8 +33,7 @@
 #include "WritableBuffer.hxx"
 
 #include <cassert>
-
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * A circular buffer.

src/util/HexFormat.hxx

@@ -34,7 +34,8 @@
 #include "StringBuffer.hxx"
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
+
 #include <stdint.h>
 
 /**

src/util/HugeAllocator.hxx

@@ -32,10 +32,9 @@
 
 #include "WritableBuffer.hxx"
 
+#include <cstddef>
 #include <utility>
 
-#include <stddef.h>
-
 #ifdef __linux__
 
 /**

src/util/OffsetPointer.hxx

@@ -29,7 +29,7 @@
 
 #pragma once
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * Offset the given pointer by the specified number of bytes.

src/util/PeakBuffer.hxx

@@ -22,7 +22,8 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
+
 #include <stdint.h>
 
 template<typename T> struct WritableBuffer;

src/util/ReusableArray.hxx

@@ -32,10 +32,9 @@
 
 #include "Compiler.h"
 
+#include <cstddef>
 #include <utility>
 
-#include <stddef.h>
-
 /**
  * Manager for a temporary array which grows as needed.  This attempts
  * to reduce the number of consecutive heap allocations and

src/util/SliceBuffer.hxx

@@ -24,11 +24,10 @@
 #include "Compiler.h"
 
 #include <cassert>
+#include <cstddef>
 #include <new>
 #include <utility>
 
-#include <stddef.h>
-
 /**
  * This class pre-allocates a certain number of objects, and allows
  * callers to allocate and free these objects ("slices").

src/util/StringStrip.hxx

@@ -32,7 +32,7 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * Skips whitespace at the beginning of the string, and returns the

src/util/StringUtil.hxx

@@ -22,7 +22,7 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 struct StringView;
 

src/util/TemplateString.hxx

@@ -30,7 +30,7 @@
 #ifndef TEMPLATE_STRING_HXX
 #define TEMPLATE_STRING_HXX
 
-#include <stddef.h>
+#include <cstddef>
 
 namespace TemplateString {
 	/**

src/util/TransformN.hxx

@@ -30,7 +30,7 @@
 #ifndef TRANSFORM_N_HXX
 #define TRANSFORM_N_HXX
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * The std::transform_n() function that is missing in the C++ standard

src/util/TruncateString.hxx

@@ -32,7 +32,7 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * Copy a string.  If the buffer is too small, then the string is

src/util/UTF8.hxx

@@ -33,7 +33,7 @@
 
 #include "Compiler.h"
 
-#include <stddef.h>
+#include <cstddef>
 
 /**
  * Is this a valid UTF-8 string?