Fix:
error: implicitly declaring library function 'exit' with type 'void (int) __attribute__((noreturn))' [-Werror,-Wimplicit-function-declaration]
--- configure.orig	2005-06-07 09:45:12.000000000 -0500
+++ configure	2022-05-18 22:46:42.000000000 -0500
@@ -5716,6 +5716,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 #include <ctype.h>
+#include <stdlib.h>
 #if ((' ' & 0x0FF) == 0x020)
 # define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
 # define TOUPPER(c) (ISLOWER(c) ? 'A' + ((c) - 'a') : (c))
@@ -24081,6 +24082,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 
+#include <stdlib.h>
 #include <string.h>
 #include <time.h>
 
--- iconv-detect.c.orig	2002-03-29 13:34:57.000000000 -0600
+++ iconv-detect.c	2022-05-18 22:52:15.000000000 -0500
@@ -22,6 +22,7 @@
 
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <iconv.h>
 
 enum {