GHA: Add OpenBSD job

[kinke]

No description provided.

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#16278"

[ibuclaw]

bash: line 6: nproc: command not found

It's sysctl -n hw.ncpu on OpenBSD (and NetBSD likewise)
https://github.com/D-Programming-GDC/gcc/blob/4bd3c9a4fcbda91e3cb425434e8ee3c7e9acfc22/buildci.sh#L81

[kinke]

Oh well, compiler test results only:

  FAILED targets:
  - runnable/xtest46_gc.d
  - runnable/a20.d
  - `unit` tests
  - runnable/bitfieldsposix32.c
  - runnable/bitfieldsdm.c
  - runnable/bitfieldsms.c
  - runnable/bug9010.d
  - runnable/cov2.d
  - runnable/dbitfieldsdm.d
  - runnable/dbitfieldsms.d
  - runnable/dbitfieldsposix32.d
  - runnable/dhry.d
  - runnable/hello-profile.d
  - runnable/profilegc_stdout.d
  - runnable/sieve.d
  - runnable/test12.d
  - runnable/test17559.d
  - runnable/test19086.d
  - runnable/test19163.d
  - runnable/test22597.c
  - runnable/test23343.c
  - runnable/test23889.c
  - runnable/testptrref_gc.d
  - runnable/testthread2.d
  - runnable/variadic.d
  - runnable/whetstone.d
  - runnable_cxx/cppa.d
  - compilable/ddoc10.d
  - compilable/ddoc1.d
  - compilable/ddoc_bom_UTF8.d
  - compilable/ddoc10325.d
  - compilable/ddoc10366.d
  - compilable/ddoc10334.d
  - compilable/ddoc10367.d
  - compilable/ddoc10869.d
  - compilable/ddoc10870.d
  - compilable/ddoc11.d
  - compilable/ddoc11479.d
  - compilable/ddoc11511.d
  - compilable/ddoc11823.d
  - compilable/ddoc12706.d
  - compilable/ddoc13.d
  - compilable/ddoc12745.d
  - compilable/ddoc13270.d
  - compilable/ddoc13645.d
  - compilable/ddoc14.d
  - compilable/ddoc14383.d
  - compilable/ddoc14413.d
  - compilable/ddoc14778.d
  - compilable/ddoc15475.d
  - compilable/ddoc17697.d
  - compilable/ddoc18361.d
  - compilable/ddoc198.d
  - compilable/ddoc19814.d
  - compilable/ddoc2.d
  - compilable/ddoc2273.d
  - compilable/ddoc3.d
  - compilable/ddoc4.d
  - compilable/ddoc4162.d
  - compilable/ddoc5.d
  - compilable/ddoc5446.d
  - compilable/ddoc6.d
  - compilable/ddoc648.d
  - compilable/ddoc6491.d
  - compilable/ddoc7.d
  - compilable/ddoc7555.d
  - compilable/ddoc7656.d
  - compilable/ddoc7715.d
  - compilable/ddoc7795.d
  - compilable/ddoc8.d
  - compilable/ddoc8271.d
  - compilable/ddoc9.d
  - compilable/ddoc8739.d
  - compilable/ddoc9037.d
  - compilable/ddoc9155.d
  - compilable/ddoc9369.d
  - compilable/ddoc9305.d
  - compilable/ddoc9475.d
  - compilable/ddoc9497a.d
  - compilable/ddoc9497b.d
  - compilable/ddoc9497c.d
  - compilable/ddoc9497d.d
  - compilable/ddoc9676a.d
  - compilable/ddoc9676b.d
  - compilable/ddoc9727.d
  - compilable/ddoc9789.d
  - compilable/ddoc9903.d
  - compilable/ddocYear.d
  - compilable/ddocbackticks.d
  - compilable/ddocunittest.d
  - compilable/issue19243.sh
  - compilable/stdcheaders.c
  - compilable/test23068.d
  - compilable/test23431.d
  - compilable/test23439.d
  - compilable/test23978.d
  - fail_compilation/fail22039.d
  - fail_compilation/fail23439.d
  - fail_compilation/impconv.d
  - fail_compilation/mixin_gc.d

I've resorted to OpenBSD's dmd package as host compiler (v2.104). It seems very slow to compile the fresh optimized DMD with it; maybe a debug build. And it definitely produces buggy executables when it comes to GC usage; all tests using -lowmem (=> enabling the GC for the compiler) crash.

Then there are many repeated issues wrt. a different diff CLI; e.g., no --strip-trailing-cr support.

I'll probably leave it at that, possibly for someone else to pick up.

[kinke]

Okay, looking much friendlier now after a bit more effort [and fortunately there's a gdiff package for GNU diff]. 14 compiler test failures remaining:

  FAILED targets:
  - runnable/xtest46_gc.d
  - `unit` tests
  - runnable/profilegc_stdout.d
  - runnable/test17559.d
  - runnable/test19086.d
  - runnable/testptrref_gc.d
  - compilable/issue19243.sh
  - compilable/test23068.d
  - compilable/test23431.d
  - compilable/test23439.d
  - compilable/test23978.d
  - fail_compilation/fail22039.d
  - fail_compilation/fail23439.d
  - fail_compilation/mixin_gc.d

7 of these are -lowmem crashes, most likely caused by a host compiler/druntime GC issue.