[llvm] [lit] Implement builtin umask (PR #94621)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

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

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/1576

Here is the relevant piece of the build log for the reference:
```
Step 6 (test-build-check-mlir-build-only-check-mlir) failure: test (failure)
0.000 [0/1/0] Running the MLIR regression tests
-- Testing: 2850 tests, 256 workers --
UNRESOLVED: MLIR :: Analysis/DataFlow/test-last-modified.mlir (1 of 2850)
******************** TEST 'MLIR :: Analysis/DataFlow/test-last-modified.mlir' FAILED ********************
Exception during script execution:
Traceback (most recent call last):
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/worker.py", line 76, in _execute_test_handle_errors
    result = test.config.test_format.execute(test, lit_config)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/formats/shtest.py", line 29, in execute
    return lit.TestRunner.executeShTest(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2295, in executeShTest
    return _runShTest(test, litConfig, useExternalSh, script, tmpBase)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2239, in _runShTest
    res = runOnce(execdir)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2215, in runOnce
    res = executeScriptInternal(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 1091, in executeScriptInternal
    exitCode, timeoutInfo = executeShCmd(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 205, in executeShCmd
    finalExitCode = _executeShCmd(cmd, shenv, results, timeoutHelper)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 712, in _executeShCmd
    res = _executeShCmd(cmd.rhs, shenv, results, timeoutHelper)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 892, in _executeShCmd
    subprocess.Popen(
TypeError: __init__() got an unexpected keyword argument 'umask'


********************
UNRESOLVED: MLIR :: Analysis/DataFlow/test-dead-code-analysis.mlir (2 of 2850)
******************** TEST 'MLIR :: Analysis/DataFlow/test-dead-code-analysis.mlir' FAILED ********************
Exception during script execution:
Traceback (most recent call last):
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/worker.py", line 76, in _execute_test_handle_errors
    result = test.config.test_format.execute(test, lit_config)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/formats/shtest.py", line 29, in execute
    return lit.TestRunner.executeShTest(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2295, in executeShTest
    return _runShTest(test, litConfig, useExternalSh, script, tmpBase)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2239, in _runShTest
    res = runOnce(execdir)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 2215, in runOnce
    res = executeScriptInternal(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 1091, in executeScriptInternal
    exitCode, timeoutInfo = executeShCmd(
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 205, in executeShCmd
    finalExitCode = _executeShCmd(cmd, shenv, results, timeoutHelper)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 712, in _executeShCmd
    res = _executeShCmd(cmd.rhs, shenv, results, timeoutHelper)
  File "/home/buildbots/llvm-external-buildbots/workers/ppc64le-mlir-rhel-test/ppc64le-mlir-rhel-clang-build/llvm-project/llvm/utils/lit/lit/TestRunner.py", line 892, in _executeShCmd
    subprocess.Popen(

```

https://github.com/llvm/llvm-project/pull/94621