Introduce prototype-style function definition for ctermid.  Upstream,

this was part of:

commit 7729e0e91afbf8d45bb322d7e2d53f417fab01ed

Author: Alexandre Oliva <aoliva@redhat.com>

Date:   Fri Nov 21 02:06:22 2014 -0200

    ctermid: return string literal, document MT-Safety pitfall

diff --git a/sysdeps/posix/ctermid.c b/sysdeps/posix/ctermid.c

index 8a0ebac8afaf23ff..94c0a6d25a5b430e 100644

--- a/sysdeps/posix/ctermid.c

+++ b/sysdeps/posix/ctermid.c

@@ -23,8 +23,7 @@

    If S is not NULL, the name is copied into it (it should be at

    least L_ctermid bytes long), otherwise a static buffer is used.  */

 char *

-ctermid (s)

-     char *s;

+ctermid (char *s)

 {

   static char name[L_ctermid];