Tell MSVC to allow non-s functions where needed

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

programs/util/pem2der.c

@@ -5,6 +5,15 @@
  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
+/* Tell MSVC that we're ok with using classic C functions even
+ * when an `_s` variant exist. For most functions, the improvements
+ * of the `_s` variants are of limited usefulness and not worth
+ * the portability headaches.
+ */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_DEPRECATE)
+#define _CRT_SECURE_NO_DEPRECATE 1
+#endif
+
 #include "mbedtls/build_info.h"
 
 #include "mbedtls/platform.h"