[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 `lld-x86_64-ubuntu-fast` running on `as-builder-4` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/33/builds/24178

<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/61/104' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/build/unittests/Support/./SupportTests-LLVM-Unit-612863-61-104.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=104 GTEST_SHARD_INDEX=61 /home/buildbot/worker/as-builder-4/ramdisk/lld-x86_64/build/unittests/Support/./SupportTests
--


Note: This is test shard 62 of 104.
[==========] Running 16 tests from 16 test suites.
[----------] Global test environment set-up.
[----------] 1 test from AlignNeededBuildAttr
[ RUN      ] AlignNeededBuildAttr.testBuildAttr
[       OK ] AlignNeededBuildAttr.testBuildAttr (0 ms)
[----------] 1 test from AlignNeededBuildAttr (0 ms total)

[----------] 1 test from CheckedArithmetic
[ RUN      ] CheckedArithmetic.CheckedAddUnsigned
[       OK ] CheckedArithmetic.CheckedAddUnsigned (0 ms)
[----------] 1 test from CheckedArithmetic (0 ms total)

[----------] 1 test from ArchName
[ RUN      ] ArchName.testAttribute
[       OK ] ArchName.testAttribute (0 ms)
[----------] 1 test from ArchName (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 HashBuilderTest/1, where TypeParam = <type>
[ RUN      ] HashBuilderTest/1.HashStdPair
[       OK ] HashBuilderTest/1.HashStdPair (0 ms)
[----------] 1 test from HashBuilderTest/1 (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 OverflowTest/0, where TypeParam = <type>
[ RUN      ] OverflowTest/0.MulResultZero
[       OK ] OverflowTest/0.MulResultZero (0 ms)
[----------] 1 test from OverflowTest/0 (0 ms total)

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

...

```

</details>

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