pthread_mutexattr_setpshared and Apache Guacamole remote desktop gateway

Hi,

Should this be on ports@?  I'm not working on a port...

TL;DR:
Does anyone have any recommendations on how to work around not having
pthread_mutexattr_setpshared in the OpenBSD pthreads library?

DETAILS:
I wanted to see if Apache Guacamole would compile on OpenBSD to server
as a remote desktop gateway.

It hasn't been too hard to get it to the final linking step.

I am getting an "undefined reference to `pthread_mutexattr_setpshared'":

../../src/libguac/.libs/libguac.so.17.0: undefined reference to
`pthread_mutexattr_setpshared'
collect2: ld returned 1 exit status
*** Error 1 in src/guacenc (Makefile:565 'guacenc': @echo " CCLD   
" guacenc;/bin/sh ../../libtool --silent --tag=CC --mode=link gcc -s...)
*** Error 1 in . (Makefile:556 'all-recursive')
*** Error 1 in /home/steve/src/guacamole-server-1.1.0 (Makefile:453
'all')


When I look at some of the code using pthread_mutexattr_setpshared, it's
not #ifdef'd or anything, so I think it's pretty much mandatory code.

pool.c:

guac_pool* guac_pool_alloc(int size) {

    pthread_mutexattr_t lock_attributes;
    guac_pool* pool = malloc(sizeof(guac_pool));

    /* If unable to allocate, just return NULL. */
    if (pool == NULL)
        return NULL;

    /* Initialize empty pool */
    pool->min_size = size;
    pool->active = 0;
    pool->__next_value = 0;
    pool->__head = NULL;
    pool->__tail = NULL;

    /* Init lock */
    pthread_mutexattr_init(&lock_attributes);

    pthread_mutexattr_setpshared(&lock_attributes,
PTHREAD_PROCESS_SHARED);
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    pthread_mutex_init(&(pool->__lock), &lock_attributes);


It looks like this is a posix (of some version) function:
https://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_mutexattr_setpshared.html

An "appropos" search in the OpenBSD man pages for "pthread_mutexattr"
returned:
https://man.openbsd.org/man3/pthread_mutexattr.3

This function is definitely missing...

I tried to see if there was a way to use pthread_mutexattr_settype to
accomplish the same thing, but got lost in the maze of documentation.

Does anyone have any recommendations on how to work around not having
pthread_mutexattr_setpshared in the OpenBSD pthreads library?

Thanks,
Steve Williams