Run autoreconf.
diff --git a/configure b/configure
index 867e2fc..d98d14a 100755
--- a/configure
+++ b/configure
@@ -15542,6 +15542,8 @@
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+#include <stdlib.h>
+#include <unistd.h>
 int main()
 {
 	int val1 = nice(1);