[clang] [llvm] [LLVM] Add GNU make jobserver support (PR #145131)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-rhel` running on `ppc64le-clang-rhel-test` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/145/builds/10051

<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)
******************** TEST 'LLVM-Unit :: Support/./SupportTests/165/208' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/unittests/Support/./SupportTests-LLVM-Unit-2726597-165-208.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=208 GTEST_SHARD_INDEX=165 /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/unittests/Support/./SupportTests
--


Note: This is test shard 166 of 208.
[==========] Running 8 tests from 8 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CheckedArithmetic
[ RUN      ] CheckedArithmetic.CheckedAddUnsigned
[       OK ] CheckedArithmetic.CheckedAddUnsigned (0 ms)
[----------] 1 test from CheckedArithmetic (0 ms total)

[----------] 1 test from Error
[ RUN      ] Error.HandleExpectedSuccess
[       OK ] Error.HandleExpectedSuccess (0 ms)
[----------] 1 test from Error (0 ms total)

[----------] 1 test from JobserverStrategyTest
[ RUN      ] JobserverStrategyTest.ParallelSortIsLimited
[       OK ] JobserverStrategyTest.ParallelSortIsLimited (51 ms)
[----------] 1 test from JobserverStrategyTest (51 ms total)

[----------] 1 test from MustacheInterpolation
[ RUN      ] MustacheInterpolation.StandaloneAmpersandWithWhitespace
[       OK ] MustacheInterpolation.StandaloneAmpersandWithWhitespace (0 ms)
[----------] 1 test from MustacheInterpolation (0 ms total)

[----------] 1 test from ProgramEnvTest
[ RUN      ] ProgramEnvTest.TestExecuteEmptyEnvironment
Note: Google Test filter = 
[==========] Running 0 tests from 0 test suites.
[==========] 0 tests from 0 test suites ran. (0 ms total)
[  PASSED  ] 0 tests.
[       OK ] ProgramEnvTest.TestExecuteEmptyEnvironment (13 ms)
[----------] 1 test from ProgramEnvTest (13 ms total)

[----------] 1 test from TimeProfiler
[ RUN      ] TimeProfiler.Begin_End_Smoke
[       OK ] TimeProfiler.Begin_End_Smoke (0 ms)
[----------] 1 test from TimeProfiler (0 ms total)

[----------] 1 test from YAMLIO
[ RUN      ] YAMLIO.TestReadBuiltInTypesint16OverError
[       OK ] YAMLIO.TestReadBuiltInTypesint16OverError (0 ms)
[----------] 1 test from YAMLIO (0 ms total)

[----------] 1 test from VirtualOutput/BackendTest
...

```

</details>

https://github.com/llvm/llvm-project/pull/145131