[llvm] [Support] Treat Windows "NUL" as the null device in writeToOutput (PR #208179)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-aarch64-windows` running on `linaro-armv8-windows-msvc-05` while building `llvm` at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/141/builds/20637

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

```
Step 6 (test) failure: build (failure)
...
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/TestDataFormatterObjCNSNumber.py (417 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/TestDataFormatterObjCNSURL.py (418 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/TestDataFormatterObjCPlain.py (419 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/TestDataFormatterObjNSException.py (420 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/cmtime/TestDataFormatterCMTime.py (421 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/nsindexpath/TestDataFormatterNSIndexPath.py (422 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-objc/nsstring/TestDataFormatterNSString.py (423 of 2629)
UNSUPPORTED: lldb-api :: functionalities/data-formatter/data-formatter-proper-plurals/TestFormattersOneIsSingular.py (424 of 2629)
PASS: lldb-api :: functionalities/data-formatter/data-formatter-ptr-matching/TestDataFormatterPtrMatching.py (425 of 2629)
PASS: lldb-api :: functionalities/data-formatter/data-formatter-ptr-to-array/TestPtrToArrayFormatting.py (426 of 2629)
FAIL: lldb-api :: functionalities/data-formatter/data-formatter-script/TestDataFormatterScript.py (427 of 2629)
******************** TEST 'lldb-api :: functionalities/data-formatter/data-formatter-script/TestDataFormatterScript.py' FAILED ********************
Script:
--
C:/Users/tcwg/scoop/apps/python/current/python.exe C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/llvm-project/lldb\test\API\dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./lib --env LLVM_INCLUDE_DIR=C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/include --env LLVM_TOOLS_DIR=C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./bin --triple aarch64-pc-windows-msvc --build-dir C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/lldb-test-build --lldb-module-cache-dir C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/lldb-test-build/module-cache-lldb\lldb-api --clang-module-cache-dir C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/lldb-test-build/module-cache-clang\lldb-api --executable C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./bin/lldb.exe --lldb-python-dir C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\Lib\site-packages --compiler C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./bin/clang.exe --dsymutil C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./bin/dsymutil.exe --make C:/Users/tcwg/scoop/shims/make.exe --llvm-tools-dir C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./bin --lldb-obj-root C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/tools/lldb --lldb-libs-dir C:/Users/tcwg/llvm-worker/lldb-aarch64-windows/build/./lib --cmake-build-type Release --skip-category=watchpoint --env LLDB_LAUNCH_FLAG_USE_PIPES=1 C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\llvm-project\lldb\test\API\functionalities\data-formatter\data-formatter-script -p TestDataFormatterScript.py
--
Exit Code: 1

Command Output (stdout):
--
Skipping the following test categories: watchpoint, libc++, libstdcxx, dwo, dsym, gmodules, debugserver, objc, fork, pexpect


--
Command Output (stderr):
--
UNSUPPORTED: LLDB (C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\bin\clang.exe-aarch64) :: test_with_run_command_dsym (TestDataFormatterScript.ScriptDataFormatterTestCase.test_with_run_command_dsym) (test case does not fall in any category of interest for this run) 

FAIL: LLDB (C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\bin\clang.exe-aarch64) :: test_with_run_command_dwarf (TestDataFormatterScript.ScriptDataFormatterTestCase.test_with_run_command_dwarf)

Log Files:

 - C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\lldb-test-build\functionalities\data-formatter\data-formatter-script\TestDataFormatterScript\Failure_test_with_run_command_dwarf.log

UNSUPPORTED: LLDB (C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\bin\clang.exe-aarch64) :: test_with_run_command_dwo (TestDataFormatterScript.ScriptDataFormatterTestCase.test_with_run_command_dwo) (test case does not fall in any category of interest for this run) 

======================================================================

FAIL: test_with_run_command_dwarf (TestDataFormatterScript.ScriptDataFormatterTestCase.test_with_run_command_dwarf)

   Test data formatter commands.

----------------------------------------------------------------------

Traceback (most recent call last):

  File "C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\llvm-project\lldb\packages\Python\lldbsuite\test\lldbtest.py", line 2186, in test_method

    return attrvalue(self)

```

</details>

https://github.com/llvm/llvm-project/pull/208179