security/gnutls: initialise libpthread

To ensure thread-safety libgnutls calls libpthread functions but to
avoid the overhead for single-threaded programs it does not link with
libpthread.  It only calls libpthread if the executable or another
library links to it.

Since 3.8.0 libgnutls calls pthread_key_create from its init function
but because it does not link with libpthread libpthread might not have
been initialised yet.  Patch the libgnutls init function so it
initialises libpthread.

PR:		278076
(cherry picked from commit 9ffc65e)

security/gnutls/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	gnutls
 DISTVERSION=	3.8.5
+PORTREVISION=	1
 CATEGORIES=	security net
 MASTER_SITES=	GNUPG/${PORTNAME}/v${DISTVERSION:R}
 

security/gnutls/files/patch-lib_global.c

@@ -0,0 +1,43 @@
+--- lib/global.c.orig	2024-04-11 15:36:24 UTC
++++ lib/global.c
+@@ -29,6 +29,13 @@
+ #include "random.h"
+ #include <gnutls/pkcs11.h>
+
++#if __FreeBSD__
++#include <sys/param.h>
++#if __FreeBSD_version >= 1400094
++#include <dlfcn.h>
++#endif
++#endif
++
+ #include "hello_ext.h" /* for _gnutls_hello_ext_init */
+ #include "supplemental.h" /* for _gnutls_supplemental_deinit */
+ #include "locks.h"
+@@ -520,6 +527,26 @@ static void _CONSTRUCTOR lib_init(void)
+ 		if (ret == 1)
+ 			return;
+ 	}
++
++#if __FreeBSD__
++#if __FreeBSD_version >= 1400094
++	/* This dlopen call initialises libpthread if it is present.  Normally
++	   this is handled by linking to libpthread but libgnutls does not link
++	   with libpthread to avoid the overhead for non-threaded programs.  */
++	(void) dlopen("libpthread.so", RTLD_LAZY | RTLD_GLOBAL | RTLD_NOLOAD);
++#else
++	/* The dlopen call above does not work correctly on older versions of
++	   FreeBSD.  Call pthread_mutex_timedlock instead.  It initialises
++	   libpthread and there's no libc stub that can preempt it.  */
++#pragma weak pthread_mutex_timedlock
++	if (pthread_mutex_timedlock != NULL) {
++		pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
++		pthread_mutex_timedlock(&lock, NULL);
++		pthread_mutex_unlock(&lock);
++		pthread_mutex_destroy(&lock);
++	}
++#endif
++#endif
+
+ 	ret = _gnutls_global_init(1);
+ 	if (ret < 0) {