"__syscall" hlc.par.gc link failure on OpenBSD

[poldy]

This function seems to have been removed between OpenBSD 7.2 & 7.3, around 6 months ago.

There is a POSIX equivalent, but because this code is in the boehm_gc submodule I can't really open a PR. I'll attach a traditional patch file here instead.

[poldy]

os_dep.c.patch

[wangp]

I guess this should be brought up upstream: https://github.com/ivmai/bdwgc

GC_OPENBSD_UTHREADS has been completely removed on the master (v8.3.x) branch:
bdwgc/bdwgc#512

[poldy]

Thanks, that PR is very relevant--it's the proper fix. I think the next release of Mercury will just fix this automatically because it has been upgraded to use bdwgc 8.2.4, which was released after that PR was accepted into upstream bdwgc. So can just close this ticket, or leave it open in case someone else hits the problem so that at least they'll know the situation.