Introduce prototype-style function definition for getttynam.  Upstream,

this was part of:

commit abccad04b4172d552dbdae948c0e567ba266ad76

Author: Joseph Myers <joseph@codesourcery.com>

Date:   Wed Jun 17 20:21:19 2015 +0000

    Fix ttyslot namespace (bug 18547).

diff --git a/misc/getttyent.c b/misc/getttyent.c

index 864f65f523de2522..018789a801b8b764 100644

--- a/misc/getttyent.c

+++ b/misc/getttyent.c

@@ -44,8 +44,7 @@ static char zapchar;

 static FILE *tf;

 struct ttyent *

-getttynam(tty)

-	const char *tty;

+getttynam (const char *tty)

 {

 	struct ttyent *t;