Fix build with opaque BIO and BIO_METHOD in LibreSSL 3.5.
LibreSSL doesn't have CRYPTO_ONCE and CRYPTO_THREAD_run_once().
Replace them with their pthread equivalents.

Index: packages/ssl/cryptolib.c
--- packages/ssl/cryptolib.c.orig
+++ packages/ssl/cryptolib.c
@@ -33,6 +33,7 @@
 */
 
 #include <config.h>
+#include <pthread.h>
 #include <string.h>
 
 #include "cryptolib.h"
@@ -293,7 +294,7 @@ bio_control(BIO* bio, int cmd, long num, void* ptr)
 static int
 bio_create(BIO* bio)
 {
-#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
    bio->shutdown = 1;
    bio->init = 1;
    bio->num = -1;
@@ -321,7 +322,7 @@ bio_destroy(BIO* bio)
    return 1;
 }
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
 /*
  * Specify the BIO read and write function structures
  */
@@ -364,6 +365,12 @@ bio_write_method(void)
  * In OpenSSL >= 1.1.0, the BIO methods are constructed
  * using functions. We initialize them exactly once.
  */
+
+#if defined(LIBRESSL_VERSION_NUMBER)
+#define CRYPTO_ONCE			pthread_once_t
+#define CRYPTO_ONCE_STATIC_INIT		PTHREAD_ONCE_INIT
+#define CRYPTO_THREAD_run_once(a, b) 	(pthread_once((a), (b)) == 0)
+#endif
 
 static CRYPTO_ONCE once_read  = CRYPTO_ONCE_STATIC_INIT;
 static CRYPTO_ONCE once_write = CRYPTO_ONCE_STATIC_INIT;