add standard header

include/nickel.h

@@ -0,0 +1,29 @@
+#ifndef __NICKEL_H_
+#define __NICKEL_H_
+
+/* common includes across the project */
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+/* includes from internal to the project */
+// ...
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// any thing we need in the top level here
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* __NICKEL_H_ */

include/nickel/linkedlist.h

@@ -1,10 +1,7 @@
 #ifndef __NICKEL_LINKEDLIST_H_
 #define __NICKEL_LINKEDLIST_H_
 
-#include <stdlib.h>
-#include <stddef.h>
-#include <stdint.h>
-#include <stdbool.h>
+#include "nickel.h"
 
 #ifdef __cplusplus
 extern "C" {

include/nickel/xalloc.h

@@ -1,12 +1,7 @@
 #ifndef __NICKEL_XALLOC_H_
 #define __NICKEL_XALLOC_H_
 
-#include <sys/types.h>
-#include <stdlib.h>
-
-#include <unistd.h>
-#include <errno.h>
-#include <string.h>
+#include "nickel.h"
 
 #ifdef __cplusplus
 extern "C" {