build: remove two #includes that don't seem to be needed

src/nano.h

@@ -113,9 +113,7 @@
 #define N_(string) gettext_noop(string)
 		/* Mark a string that will be sent to gettext() later. */
 
-#include <stddef.h>
 #include <stdlib.h>
-#include <sys/types.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <regex.h>