diff -ruN hdf5-1.12.1-orig/configure hdf5-1.12.1/configure
--- hdf5-1.12.1-orig/configure	2021-07-01 16:31:55.000000000 -0500
+++ hdf5-1.12.1/configure	2021-10-27 04:12:01.000000000 -0500
@@ -29638,7 +29638,7 @@
 else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-
+#include  <stdlib.h>
                 #include "szlib.h"
 
 #ifdef FC_DUMMY_MAIN