[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 `llvm-clang-x86_64-gcc-ubuntu-no-asserts` running on `doug-worker-6` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/202/builds/3610

<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/6/13' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/buildbot/buildbot-root/gcc-no-asserts/build/unittests/Support/./SupportTests-LLVM-Unit-1843134-6-13.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=13 GTEST_SHARD_INDEX=6 /home/buildbot/buildbot-root/gcc-no-asserts/build/unittests/Support/./SupportTests
--


Note: This is test shard 7 of 13.
[==========] Running 125 tests from 88 test suites.
[----------] Global test environment set-up.
[----------] 2 tests from AlignmentTest
[ RUN      ] AlignmentTest.AlignConstant
[       OK ] AlignmentTest.AlignConstant (0 ms)
[ RUN      ] AlignmentTest.offsetToAlignment
[       OK ] AlignmentTest.offsetToAlignment (0 ms)
[----------] 2 tests from AlignmentTest (0 ms total)

[----------] 1 test from AllocatorTest
[ RUN      ] AllocatorTest.TestSlowerSlabGrowthDelay
[       OK ] AllocatorTest.TestSlowerSlabGrowthDelay (0 ms)
[----------] 1 test from AllocatorTest (0 ms total)

[----------] 1 test from CPUAlignBuildAttr
[ RUN      ] CPUAlignBuildAttr.testBuildAttr
[       OK ] CPUAlignBuildAttr.testBuildAttr (0 ms)
[----------] 1 test from CPUAlignBuildAttr (0 ms total)

[----------] 1 test from AlignPreservedBuildAttr
[ RUN      ] AlignPreservedBuildAttr.testBuildAttr
[       OK ] AlignPreservedBuildAttr.testBuildAttr (0 ms)
[----------] 1 test from AlignPreservedBuildAttr (0 ms total)

[----------] 1 test from Base64Test
[ RUN      ] Base64Test.DecodeBase64
[       OK ] Base64Test.DecodeBase64 (0 ms)
[----------] 1 test from Base64Test (0 ms total)

[----------] 1 test from BinaryStreamTest
[ RUN      ] BinaryStreamTest.StreamReaderEnum
[       OK ] BinaryStreamTest.StreamReaderEnum (0 ms)
[----------] 1 test from BinaryStreamTest (0 ms total)

[----------] 1 test from BlockFrequencyTest
[ RUN      ] BlockFrequencyTest.OneToZero
[       OK ] BlockFrequencyTest.OneToZero (0 ms)
[----------] 1 test from BlockFrequencyTest (0 ms total)

[----------] 1 test from BranchProbabilityTest
[ RUN      ] BranchProbabilityTest.Accessors
[       OK ] BranchProbabilityTest.Accessors (0 ms)
...

```

</details>

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