systat: Remove obsolete copyright string

This is unused, so remove it. We don't put a copyright string in most of
the other binaries. This one doesn't need one either.

Sponsored by:		Netflix

usr.bin/systat/main.c

@@ -37,12 +37,6 @@ __FBSDID("$FreeBSD$");
 static const char sccsid[] = "@(#)main.c	8.1 (Berkeley) 6/6/93";
 #endif
 
-#ifndef lint
-static const char copyright[] __unused =
-"@(#) Copyright (c) 1980, 1992, 1993\n\
-	The Regents of the University of California.  All rights reserved.\n";
-#endif
-
 #include <sys/param.h>
 #include <sys/time.h>
 #include <sys/sysctl.h>