Introduce prototype-style definitions for putgrent, putpwent.  Upstream,
this was done as part of this commit (not backported here):

commit 676599b36a92f3c201c5682ee7a5caddd9f370a4
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Oct 2 11:34:13 2015 +0200

    Harden putpwent, putgrent, putspent, putspent against injection [BZ #18724]

diff --git a/grp/putgrent.c b/grp/putgrent.c
index 176a7a15d8bb6ec2..1d69136c30c81bcd 100644
--- a/grp/putgrent.c
+++ b/grp/putgrent.c
@@ -27,9 +27,7 @@
 /* Write an entry to the given stream.
    This must know the format of the group file.  */
 int
-putgrent (gr, stream)
-     const struct group *gr;
-     FILE *stream;
+putgrent (const struct group *gr, FILE *stream)
 {
   int retval;
 
diff --git a/pwd/putpwent.c b/pwd/putpwent.c
index e9470ed1012a1789..9a9f04dcf4b596ee 100644
--- a/pwd/putpwent.c
+++ b/pwd/putpwent.c
@@ -24,9 +24,7 @@
 /* Write an entry to the given stream.
    This must know the format of the password file.  */
 int
-putpwent (p, stream)
-     const struct passwd *p;
-     FILE *stream;
+putpwent (const struct passwd *p, FILE *stream)
 {
   if (p == NULL || stream == NULL)
     {