Use correct version of snprintf on Windows

platform.h defines MBEDTLS_PLATFORM_STD_SNPRINTF based on _WIN32. But while defining macro mbedtls_snprintf it sets it to STD C snprintf that is deprecated on Windows.
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index ed10775..2e21f03 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -210,7 +210,7 @@
 #if defined(MBEDTLS_PLATFORM_SNPRINTF_MACRO)
 #define mbedtls_snprintf   MBEDTLS_PLATFORM_SNPRINTF_MACRO
 #else
-#define mbedtls_snprintf   snprintf
+#define mbedtls_snprintf   MBEDTLS_PLATFORM_STD_SNPRINTF
 #endif /* MBEDTLS_PLATFORM_SNPRINTF_MACRO */
 #endif /* MBEDTLS_PLATFORM_SNPRINTF_ALT */