add test with iwyu and fix all headers accordingly

utils/http.h

@@ -20,6 +20,8 @@
 #define _MFSHELL_HTTP_H_
 
 #include <jansson.h>
+#include <stddef.h>
+#include <stdio.h>
 
 typedef struct mfhttp mfhttp;
 

utils/json.c

@@ -18,7 +18,6 @@
 
 
 #include <stdlib.h>
-#include <string.h>
 
 #include "json.h"
 #include "stringv.h"

utils/strings.c

@@ -17,11 +17,12 @@
  */
 
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdarg.h>
-#include <string.h>
 #include <ctype.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "strings.h"
 #include "stringv.h"

utils/strings.h

@@ -20,8 +20,6 @@
 #ifndef _STR_TOOLS_H_
 #define _STR_TOOLS_H_
 
-#include <stdint.h>
-
 char*       strdup_printf(char* fmt, ...);
 
 char*       strdup_join(char *string1,char *string2);

utils/stringv.c

@@ -17,9 +17,8 @@
  */
 
 
+#include <stdint.h>
 #include <stdlib.h>
-#include <stdio.h>
-#include <stdarg.h>
 #include <string.h>
 
 #include "stringv.h"

utils/stringv.h

@@ -20,7 +20,7 @@
 #ifndef _STRING_V_H_
 #define _STRING_V_H_
 
-#include <stdint.h>
+#include <stddef.h>
 
 #define     STRINGV_FREE_ALL    1