[llvm] [Support] Fix building on FreeBSD and OpenBSD (PR #127005)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-aarch64-ubuntu` running on `linaro-lldb-aarch64-ubuntu` while building `llvm` at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/12681

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test) failure: build (failure)
...
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentBreakpointDelayBreakpointOneSignal.py (611 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentCrashWithWatchpoint.py (612 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentBreakpointsDelayedBreakpointOneWatchpoint.py (613 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentCrashWithWatchpointBreakpointSignal.py (614 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentDelaySignalBreak.py (615 of 2089)
PASS: lldb-api :: functionalities/progress_reporting/TestTrimmedProgressReporting.py (616 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentDelaySignalWatch.py (617 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentDelayWatchBreak.py (618 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentDelayedCrashWithBreakpointSignal.py (619 of 2089)
PASS: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentDelayedCrashWithBreakpointWatchpoint.py (620 of 2089)
FAIL: lldb-api :: functionalities/thread/concurrent_events/TestConcurrentManyBreakpoints.py (621 of 2089)
******************** TEST 'lldb-api :: functionalities/thread/concurrent_events/TestConcurrentManyBreakpoints.py' FAILED ********************
Script:
--
/usr/bin/python3.10 /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./lib --env LLVM_INCLUDE_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/include --env LLVM_TOOLS_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin --arch aarch64 --build-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex --lldb-module-cache-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/lldb --compiler /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/clang --dsymutil /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin --lldb-obj-root /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb --lldb-libs-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./lib /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/test/API/functionalities/thread/concurrent_events -p TestConcurrentManyBreakpoints.py
--
Exit Code: 1

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 89d636ba91924c945d39f02f261863b709249744)
  clang revision 89d636ba91924c945d39f02f261863b709249744
  llvm revision 89d636ba91924c945d39f02f261863b709249744
Skipping the following test categories: ['libc++', 'dsym', 'gmodules', 'debugserver', 'objc']

--
Command Output (stderr):
--
FAIL: LLDB (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/bin/clang-aarch64) :: test (TestConcurrentManyBreakpoints.ConcurrentManyBreakpoints)
======================================================================
FAIL: test (TestConcurrentManyBreakpoints.ConcurrentManyBreakpoints)
   Test 100 breakpoints from 100 threads.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/packages/Python/lldbsuite/test/decorators.py", line 148, in wrapper
    return func(*args, **kwargs)
  File "/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/test/API/functionalities/thread/concurrent_events/TestConcurrentManyBreakpoints.py", line 16, in test
    self.do_thread_actions(num_breakpoint_threads=100)
  File "/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/packages/Python/lldbsuite/test/concurrent_base.py", line 225, in do_thread_actions
    self.assertEqual(
AssertionError: 1 != 101 : Expected to see 101 threads, but seeing 1. Details:
thread 1 running due to none at
	
Config=aarch64-/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/bin/clang
----------------------------------------------------------------------
Ran 1 test in 2.931s

FAILED (failures=1)


```

</details>

https://github.com/llvm/llvm-project/pull/127005