diff -ruN libelf-0.8.13-orig/configure libelf-0.8.13/configure
--- libelf-0.8.13-orig/configure	2008-05-23 03:18:03.000000000 -0500
+++ libelf-0.8.13/configure	2021-01-29 05:06:22.000000000 -0600
@@ -1115,6 +1115,7 @@
 #line 1116 "configure"
 #include "confdefs.h"
 #include <ctype.h>
+#include <stdlib.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
 #define TOUPPER(c) (ISLOWER(c) ? 'A' + ((c) - 'a') : (c))
 #define XOR(e, f) (((e) && !(f)) || (!(e) && (f)))
@@ -1484,6 +1485,7 @@
 #line 1485 "configure"
 #include "confdefs.h"
 #include <stdio.h>
+#include <stdlib.h>
 main()
 {
   FILE *f=fopen("conftestval", "w");
@@ -1523,6 +1525,7 @@
 #line 1524 "configure"
 #include "confdefs.h"
 #include <stdio.h>
+#include <stdlib.h>
 main()
 {
   FILE *f=fopen("conftestval", "w");
@@ -1562,6 +1565,7 @@
 #line 1563 "configure"
 #include "confdefs.h"
 #include <stdio.h>
+#include <stdlib.h>
 main()
 {
   FILE *f=fopen("conftestval", "w");
@@ -1601,6 +1605,7 @@
 #line 1602 "configure"
 #include "confdefs.h"
 #include <stdio.h>
+#include <stdlib.h>
 main()
 {
   FILE *f=fopen("conftestval", "w");
@@ -1641,6 +1646,7 @@
 #line 1642 "configure"
 #include "confdefs.h"
 #include <stdio.h>
+#include <stdlib.h>
 main()
 {
   FILE *f=fopen("conftestval", "w");
@@ -2236,6 +2242,8 @@
   cat > conftest.$ac_ext <<EOF
 #line 2238 "configure"
 #include "confdefs.h"
+#include <stdlib.h>
+#include <unistd.h>
 
 /* Thanks to Mike Haertel and Jim Avera for this test.
    Here is a matrix of mmap possibilities:
@@ -2527,6 +2535,7 @@
 #line 2528 "configure"
 #include "confdefs.h"
 #include "confdefs.h"
+#include <stdlib.h>
 #if HAVE_MEMMOVE
 extern void *memmove();
 #else