fixed stddef.h include

src/starter/starterstroke.c

@@ -17,7 +17,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <linux/stddef.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <errno.h>

src/starter/starterwhack.c

@@ -17,7 +17,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <linux/stddef.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <errno.h>
 

src/stroke/stroke.c

@@ -22,7 +22,7 @@
 #include <dirent.h>
 #include <errno.h>
 #include <stdio.h>
-#include <linux/stddef.h>
+#include <stddef.h>
 
 #include "stroke.h"
 #include "stroke_keywords.h"