Make username size dependant on MAXLOGNAME in sys/param.h. Was

previously hard-coded at 16 characters (and possibly overflowing
the field when NUL terminating a username of exactly 16 characters
in length).

libexec/getty/main.c

@@ -93,7 +93,7 @@ struct termios tmode, omode;
 int crmod, digit, lower, upper;
 
 char	hostname[MAXHOSTNAMELEN];
-char	name[16];
+char	name[MAXLOGNAME+1];
 char	dev[] = _PATH_DEV;
 char	ttyn[32];
 
@@ -533,7 +533,7 @@ getname()
 
 		if (c == EOT || c == CTRL('d'))
 			exit(1);
-		if (c == '\r' || c == '\n' || np >= &name[sizeof name]) {
+		if (c == '\r' || c == '\n' || np >= &name[sizeof name-1]) {
 			putf("\r\n");
 			break;
 		}