Fix missing include in some pkey programs
The programs assume that including "pk.h" brings up "bignum.h". When
MBEDTLS_USE_TINYCRYPT is enabled and MBEDTLS_RSA_C is disabled, that
assumption no longer holds. Fix that by explicitly including bignum.h from the
programs that need it.
This is a bug pre-existing to this PR, fixed here to enable the inclusion of a
test with a config that happens to reveal it.
diff --git a/programs/pkey/key_app_writer.c b/programs/pkey/key_app_writer.c
index 6096429..16dd1b6 100644
--- a/programs/pkey/key_app_writer.c
+++ b/programs/pkey/key_app_writer.c
@@ -39,6 +39,7 @@
#if defined(MBEDTLS_PK_WRITE_C) && defined(MBEDTLS_FS_IO)
#include "mbedtls/error.h"
#include "mbedtls/pk.h"
+#include "mbedtls/bignum.h"
#include "mbedtls/error.h"
#include <stdio.h>