Backport to fix some clang16 issues.
https://bugs.gentoo.org/870631

https://github.com/phokz/pwauth/commit/c1e7fd9af0
From: Philip Prindeville <philipp@redfish-solutions.com>
Date: Mon, 23 Jul 2018 13:41:47 -0600
Subject: [PATCH] Quiet compiler warnings for signatures

There are missing/incomplete function declarations.  Also a missing
header.
--- a/lastlog.c
+++ b/lastlog.c
@@ -31,6 +31,8 @@
  * =======================================================================
  */
 
+#include <time.h>
+
 #include "pwauth.h"
 
 /* LASTLOG - update the system's lastlog */
--- a/main.c
+++ b/main.c
@@ -44,6 +44,7 @@ int server_uids[]= {SERVER_UIDS, 0};
 #endif
 
 
+int
 main(int argc, char **argv)
 {
 #ifdef ENV_METHOD
--- a/pwauth.h
+++ b/pwauth.h
@@ -127,3 +127,7 @@ extern int haveuid;
 #ifndef BFSZ
 # define BFSZ 1024
 #endif
+
+void snooze(int seconds);
+void lastlog(void);
+int check_auth(char *login, char *passwd);
--- a/snooze.c
+++ b/snooze.c
@@ -42,6 +42,7 @@
  * sleep time, if other pwauth processes are in sleeps.
  */
 
+void
 snooze(int seconds)
 {
     int slfd;