Document and/or fix stuff found by Sebastian in code review

Thanks to Sebastian for his code-review of the bufferevents patch series.x

src/common/crypto.h

@@ -238,7 +238,8 @@ void secret_to_key(char *key_out, size_t key_out_len, const char *secret,
                    size_t secret_len, const char *s2k_specifier);
 
 #ifdef CRYPTO_PRIVATE
-/* Prototypes for private functions only used by tortls.c and crypto.c */
+/* Prototypes for private functions only used by tortls.c, crypto.c, and the
+ * unit tests. */
 struct rsa_st;
 struct evp_pkey_st;
 struct dh_st;

src/common/tortls.c

@@ -1706,9 +1706,9 @@ tor_tls_init_bufferevent(tor_tls_t *tls, struct bufferevent *bufev_in,
     tor_assert(evbuffer_get_length(bufferevent_get_output(bufev_in)) == 0);
     tor_assert(BIO_number_read(SSL_get_rbio(tls->ssl)) == 0);
     tor_assert(BIO_number_written(SSL_get_rbio(tls->ssl)) == 0);
+    bufferevent_free(bufev_in);
   }
   tls->state = TOR_TLS_ST_BUFFEREVENT;
-  bufferevent_free(bufev_in);
   out = bufferevent_openssl_socket_new(tor_libevent_get_base(),
                                        socket,
                                        tls->ssl,

src/common/tortls.h

@@ -64,9 +64,7 @@ int tor_tls_check_lifetime(tor_tls_t *tls, int tolerance);
 int tor_tls_read(tor_tls_t *tls, char *cp, size_t len);
 int tor_tls_write(tor_tls_t *tls, const char *cp, size_t n);
 int tor_tls_handshake(tor_tls_t *tls);
-#if defined(USE_BUFFEREVENTS) || defined(TORTLS_PRIVATE)
 int tor_tls_finish_handshake(tor_tls_t *tls);
-#endif
 int tor_tls_renegotiate(tor_tls_t *tls);
 void tor_tls_block_renegotiation(tor_tls_t *tls);
 int tor_tls_shutdown(tor_tls_t *tls);