[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-m68k-linux-cross` running on `suse-gary-m68k-cross` while building `clang,llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/27/builds/16988

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'LLVM-Unit :: Support/./SupportTests/10/52' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/unittests/Support/./SupportTests-LLVM-Unit-653666-10-52.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=52 GTEST_SHARD_INDEX=10 /var/lib/buildbot/workers/suse-gary-m68k-cross/clang-m68k-linux-cross/stage1/unittests/Support/./SupportTests
--


Note: This is test shard 11 of 52.
[==========] Running 32 tests from 32 test suites.
[----------] Global test environment set-up.
[----------] 1 test from AlignmentTest
[ RUN      ] AlignmentTest.AlignConstant
[       OK ] AlignmentTest.AlignConstant (0 ms)
[----------] 1 test from AlignmentTest (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 BranchProbabilityTest
[ RUN      ] BranchProbabilityTest.Accessors
[       OK ] BranchProbabilityTest.Accessors (0 ms)
[----------] 1 test from BranchProbabilityTest (0 ms total)

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

[----------] 1 test from CommandLineTest
[ RUN      ] CommandLineTest.PositionalEatArgsError
[       OK ] CommandLineTest.PositionalEatArgsError (0 ms)
[----------] 1 test from CommandLineTest (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 EndianStream
[ RUN      ] EndianStream.WriteArrayLE
[       OK ] EndianStream.WriteArrayLE (0 ms)
[----------] 1 test from EndianStream (0 ms total)

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

...

```

</details>

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