Add missing stdlib.h header to rsa sample programs
diff --git a/programs/pkey/rsa_decrypt.c b/programs/pkey/rsa_decrypt.c
index 292092c..5d18267 100644
--- a/programs/pkey/rsa_decrypt.c
+++ b/programs/pkey/rsa_decrypt.c
@@ -30,6 +30,7 @@
 #include "polarssl/platform.h"
 #else
 #include <stdio.h>
+#include <stdlib.h>
 #define polarssl_printf     printf
 #define polarssl_exit       exit
 #endif