[llvm] [YAML][NFC] precommit wrong test case (PR #131782)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `arc-builder` running on `arc-worker` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/3/builds/13569

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
...
18.375 [2/17/61] Linking CXX executable unittests/MI/MITests
18.600 [2/16/62] Linking CXX executable unittests/IR/IRTests
18.894 [2/15/63] Linking CXX executable unittests/Transforms/Coroutines/CoroTests
19.198 [2/14/64] Linking CXX executable unittests/Transforms/Instrumentation/InstrumentationTests
19.202 [2/13/65] Linking CXX executable unittests/ExecutionEngine/MCJIT/MCJITTests
19.221 [2/12/66] Linking CXX executable unittests/Target/TargetMachineCTests
19.274 [2/11/67] Linking CXX executable unittests/Passes/PassBuilderBindings/PassesBindingsTests
19.331 [2/10/68] Linking CXX executable unittests/tools/llvm-cfi-verify/CFIVerifyTests
19.712 [2/9/69] Linking CXX executable unittests/Passes/Plugins/PluginsTests
19.794 [2/8/70] Building CXX object unittests/Support/CMakeFiles/SupportTests.dir/YAMLIOTest.cpp.o
FAILED: unittests/Support/CMakeFiles/SupportTests.dir/YAMLIOTest.cpp.o 
/usr/bin/c++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Iunittests/Support -I/buildbot/worker/arc-folder/llvm-project/llvm/unittests/Support -Iinclude -I/buildbot/worker/arc-folder/llvm-project/llvm/include -I/buildbot/worker/arc-folder/llvm-project/third-party/unittest/googletest/include -I/buildbot/worker/arc-folder/llvm-project/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wno-dangling-else -Wno-variadic-macros -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -std=c++17 -MD -MT unittests/Support/CMakeFiles/SupportTests.dir/YAMLIOTest.cpp.o -MF unittests/Support/CMakeFiles/SupportTests.dir/YAMLIOTest.cpp.o.d -o unittests/Support/CMakeFiles/SupportTests.dir/YAMLIOTest.cpp.o -c /buildbot/worker/arc-folder/llvm-project/llvm/unittests/Support/YAMLIOTest.cpp
/buildbot/worker/arc-folder/llvm-project/llvm/unittests/Support/YAMLIOTest.cpp:1280:20: error: explicit specialization of 'template<class T> struct llvm::yaml::MappingTraits' outside its namespace must use a nested-name-specifier [-fpermissive]
 1280 | template <> struct MappingTraits<V> {
      |                    ^~~~~~~~~~~~~~~~
19.989 [2/7/71] Linking CXX executable unittests/Transforms/Utils/UtilsTests
20.164 [2/6/72] Linking CXX executable unittests/Target/X86/X86Tests
21.182 [2/5/73] Linking CXX executable unittests/Transforms/Scalar/ScalarTests
21.253 [2/4/74] Linking CXX executable tools/clang/unittests/Interpreter/ClangReplInterpreterTests
21.472 [2/3/75] Linking CXX executable unittests/tools/llvm-mca/LLVMMCATests
21.626 [2/2/76] Linking CXX executable unittests/tools/llvm-exegesis/LLVMExegesisTests
22.076 [2/1/77] Linking CXX executable tools/clang/unittests/Interpreter/ExceptionTests/ClangReplInterpreterExceptionTests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/131782