Clean up code by removing pre-C99 struct hack preprocessor magic.

Approved by:	randi (maintainer)

usr.sbin/sysinstall/sysinstall.h

@@ -228,13 +228,7 @@ typedef struct _dmenu {
     char *prompt;			/* Our prompt			*/
     char *helpline;			/* Line of help at bottom	*/
     char *helpfile;			/* Help file for "F1"		*/
-#if (__STDC_VERSION__ >= 199901L) || (__GNUC__ >= 3) 
     dialogMenuItem items[];		/* Array of menu items		*/
-#elif __GNUC__
-    dialogMenuItem items[0];		/* Array of menu items		*/
-#else
-#error "Create hack for C89 and K&R compilers."
-#endif
 } DMenu;
 
 /* An rc.conf variable */