needed for exit() prototype

--- a/libhfsp/src/os.c
+++ b/libhfsp/src/os.c
@@ -46,6 +46,7 @@ int fstat(int, struct stat *);
 # endif
 
 # include <stdio.h>
+# include <stdlib.h>
 
 
 # include <errno.h>
--- a/libhfsp/src/record.c
+++ b/libhfsp/src/record.c
@@ -32,6 +32,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <string.h>
+#include <stdlib.h>
 
 #include "libhfsp.h"
 #include "hfstime.h"