[llvm] [llvm][support] Add LDBG macro. (PR #143704)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-win-fast` running on `as-builder-3` while building `llvm` at step 7 "test-build-unified-tree-check-llvm-unit".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/2/builds/29743

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

```
Step 7 (test-build-unified-tree-check-llvm-unit) failure: test (failure)
...
[733/756] Building CXX object unittests\XRay\CMakeFiles\XRayTests.dir\FDRRecordsTest.cpp.obj
[734/756] Building CXX object unittests\XRay\CMakeFiles\XRayTests.dir\ProfileTest.cpp.obj
[735/756] Building CXX object unittests\tools\llvm-mca\CMakeFiles\LLVMMCATests.dir\MCATestBase.cpp.obj
[736/756] Building CXX object unittests\tools\llvm-profgen\CMakeFiles\LLVMProfgenTests.dir\ContextCompressionTest.cpp.obj
[737/756] Linking CXX executable unittests\TextAPI\TextAPITests.exe
[738/756] Linking CXX executable unittests\tools\llvm-profgen\LLVMProfgenTests.exe
[739/756] Linking CXX executable unittests\XRay\XRayTests.exe
[740/756] Linking CXX executable unittests\tools\llvm-mca\LLVMMCATests.exe
[741/756] Linking CXX executable unittests\tools\llvm-profdata\LLVMProfdataTests.exe
[742/756] Building CXX object unittests\Support\CMakeFiles\SupportTests.dir\DebugLogTest.cpp.obj
FAILED: unittests/Support/CMakeFiles/SupportTests.dir/DebugLogTest.cpp.obj 
C:\ninja\ccache.exe C:\PROGRA~1\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1438~1.331\bin\Hostx64\x64\cl.exe  /nologo /TP -DEXPERIMENTAL_KEY_INSTRUCTIONS -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\Support -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\Support -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\include -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\include -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\third-party\unittest\googletest\include -IC:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\third-party\unittest\googlemock\include /DWIN32 /D_WINDOWS   /Zc:inline /Zc:preprocessor /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd5105 -wd4324 -wd4251 -wd4275 -w14062 -we4238 /Gw /O2 /Ob2 /DNDEBUG -MD  /EHs-c- /GR- -std:c++17 /showIncludes /Founittests\Support\CMakeFiles\SupportTests.dir\DebugLogTest.cpp.obj /Fdunittests\Support\CMakeFiles\SupportTests.dir\ /FS -c C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\Support\DebugLogTest.cpp
C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\llvm-project\llvm\unittests\Support\DebugLogTest.cpp(69): error C2466: cannot allocate an array of constant size 0
[743/756] Linking CXX executable unittests\Passes\PassBuilderBindings\PassesBindingsTests.exe
[744/756] Linking CXX executable unittests\IR\IRTests.exe
[745/756] Linking CXX executable unittests\Transforms\Vectorize\VectorizeTests.exe
[746/756] Linking CXX executable unittests\Transforms\Vectorize\SandboxVectorizer\SandboxVectorizerTests.exe
[747/756] Linking CXX executable unittests\Transforms\IPO\IPOTests.exe
[748/756] Linking CXX executable unittests\Target\TargetMachineCTests.exe
[749/756] Linking CXX executable unittests\Target\ARM\ARMTests.exe
[750/756] Linking CXX executable unittests\tools\llvm-exegesis\LLVMExegesisTests.exe
[751/756] Linking CXX executable unittests\Transforms\Coroutines\CoroTests.exe
[752/756] Linking CXX executable unittests\Transforms\Instrumentation\InstrumentationTests.exe
[753/756] Linking CXX executable unittests\Transforms\Utils\UtilsTests.exe
[754/756] Linking CXX executable unittests\Transforms\Scalar\ScalarTests.exe
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/143704