Fix build with opaque structs in LibreSSL 3.5

Index: src/test/test_crypto_openssl.c
--- src/test/test_crypto_openssl.c.orig
+++ src/test/test_crypto_openssl.c
@@ -49,7 +49,7 @@ test_crypto_rng_engine(void *arg)
   ;
 }
 
-#ifndef OPENSSL_1_1_API
+#if !defined(OPENSSL_1_1_API) && !defined(LIBRESSL_VERSION_NUMBER)
 #define EVP_ENCODE_CTX_new() tor_malloc_zero(sizeof(EVP_ENCODE_CTX))
 #define EVP_ENCODE_CTX_free(ctx) tor_free(ctx)
 #endif
