Reencode certificates in X509_sign_ctx.

Reencode certificates in X509_sign_ctx as well as X509_sign.

This was causing a problem in the x509 application when it modified an
existing certificate.

crypto/x509/x_all.c

@@ -98,6 +98,7 @@ int X509_sign(X509 *x, EVP_PKEY *pkey, const EVP_MD *md)
 
 int X509_sign_ctx(X509 *x, EVP_MD_CTX *ctx)
 	{
+	x->cert_info->enc.modified = 1;
 	return ASN1_item_sign_ctx(ASN1_ITEM_rptr(X509_CINF),
 		x->cert_info->signature,
 		x->sig_alg, x->signature, x->cert_info, ctx);