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

[Jay Foad via llvm-commits]

================
@@ -0,0 +1,18 @@
+# Check the umask command
+
+# RUN: not %{lit} -a -v %{inputs}/shtest-umask | FileCheck -match-full-lines %s
+
+# CHECK: -- Testing: 3 tests{{.*}}
+
+# CHECK-LABEL: FAIL: shtest-umask :: umask-bad-arg.txt ({{[^)]*}})
+# CHECK: umask bad
+# CHECK: # | Error: 'umask': invalid literal {{.*}}
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jayfoad wrote:

That's pretty weird since it is generated by:
```python
        raise InternalShellError(cmd, "Error: 'umask': %s" % str(err))
```

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