Move max() to jansson_private.h, define only if not already defined

On some platforms (Visual C++ for one) the standard library already
defines max() as a macro.

src/Makefile.am

@@ -11,7 +11,6 @@ libjansson_la_SOURCES = \
 	strbuffer.h \
 	utf.c \
 	utf.h \
-	util.h \
 	value.c
 libjansson_la_LDFLAGS = \
 	-export-symbols-regex '^json_' \

src/jansson_private.h

@@ -15,6 +15,11 @@
 #define container_of(ptr_, type_, member_)  \
     ((type_ *)((char *)ptr_ - offsetof(type_, member_)))
 
+/* On some platforms, max() may already be defined */
+#ifndef max
+#define max(a, b)  ((a) > (b) ? (a) : (b))
+#endif
+
 typedef struct {
     json_t json;
     hashtable_t hashtable;

src/strbuffer.c

@@ -8,8 +8,8 @@
 #define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
+#include "jansson_private.h"
 #include "strbuffer.h"
-#include "util.h"
 
 #define STRBUFFER_MIN_SIZE  16
 #define STRBUFFER_FACTOR    2

src/util.h

@@ -1,13 +0,0 @@
-/*
- * Copyright (c) 2009, 2010 Petri Lehtinen <petri@digip.org>
- *
- * Jansson is free software; you can redistribute it and/or modify
- * it under the terms of the MIT license. See LICENSE for details.
- */
-
-#ifndef UTIL_H
-#define UTIL_H
-
-#define max(a, b)  ((a) > (b) ? (a) : (b))
-
-#endif

src/value.c

@@ -15,7 +15,6 @@
 #include "hashtable.h"
 #include "jansson_private.h"
 #include "utf.h"
-#include "util.h"
 
 
 static JSON_INLINE void json_init(json_t *json, json_type type)