fix check

Reviewed-by: NKurt Roeckx <kurt@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>

crypto/evp/bio_b64.c

@@ -122,12 +122,12 @@ static int b64_new(BIO *bi)
 
     ctx->cont = 1;
     ctx->start = 1;
+    ctx->base64 = EVP_ENCODE_CTX_new();
     if (ctx->base64 == NULL) {
         OPENSSL_free(ctx);
         return 0;
     }
 
-    ctx->base64 = EVP_ENCODE_CTX_new();
     BIO_set_data(bi, ctx);
     BIO_set_init(bi, 1);