[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 `ml-opt-rel-x86-64` running on `ml-opt-rel-x86-64-b1` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/185/builds/26488

<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/9/26' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/b/ml-opt-rel-x86-64-b1/build/unittests/Support/./SupportTests-LLVM-Unit-1505418-9-26.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=26 GTEST_SHARD_INDEX=9 /b/ml-opt-rel-x86-64-b1/build/unittests/Support/./SupportTests
--


Note: This is test shard 10 of 26.
[==========] Running 64 tests from 54 test suites.
[----------] Global test environment set-up.
[----------] 1 test from AlignmentTest
[ RUN      ] AlignmentTest.AlignOfConstant
[       OK ] AlignmentTest.AlignOfConstant (0 ms)
[----------] 1 test from AlignmentTest (0 ms total)

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

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

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

[----------] 1 test from BalancedPartitioningTest
[ RUN      ] BalancedPartitioningTest.MoveGain
[       OK ] BalancedPartitioningTest.MoveGain (0 ms)
[----------] 1 test from BalancedPartitioningTest (0 ms total)

[----------] 1 test from CastingTest
[ RUN      ] CastingTest.isa_and_nonnull
Classof: 0x56183719a461
Classof: 0x56183719a461
[       OK ] CastingTest.isa_and_nonnull (0 ms)
[----------] 1 test from CastingTest (0 ms total)

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

[----------] 2 tests from CommandLineTest
[ RUN      ] CommandLineTest.TokenizeConfigFile11
[       OK ] CommandLineTest.TokenizeConfigFile11 (0 ms)
...

```

</details>

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