https://github.com/mtsuszycki/whowatch/pull/12

From 62688e7316de7d4c80591f83afc97d55d73ad272 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Sat, 26 Nov 2022 17:45:23 +0100
Subject: [PATCH] configure.ac: Do not call undeclared exit function

Implicit function declarations were removed from the C language in
1999, and future compilers are likely to treat them as errors by
default.
--- a/configure.ac
+++ b/configure.ac
@@ -120,8 +120,8 @@ fd_set rfds;
 struct timeval tv = {1, 0};
 FD_ZERO(&rfds); FD_SET(0,&rfds);
 select(1,&rfds,0,0,&tv);
-if(tv.tv_sec == 0) exit(0);
-else exit(1);
+if(tv.tv_sec == 0) return 0;
+else return 1;
 }
 ]])],[AC_MSG_RESULT(yes); AC_DEFINE([RETURN_TV_IN_SELECT],[1],[define if select() modifies the time value])],[AC_MSG_RESULT(no)],[AC_MSG_RESULT(no)])