protect against multiple inclusions, commented text after #endif

h/arch.h

@@ -3,6 +3,10 @@
  * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
  * See the copyright notice in the ACK home directory, in the file "Copyright".
  */
+
+#ifndef __ARCH_H_INCLUDED
+#define __ARCH_H_INCLUDED
+
 #define	ARMAG	0177545
 #define AALMAG	0177454
 
@@ -17,3 +21,5 @@ struct	ar_hdr {
 
 #define AR_TOTAL	26
 #define AR_SIZE		22
+
+#endif /* __ARCH_H_INCLUDED */