[llvm] [llvm-calc-occupancy] Add an AMDGPU occupancy calculator tool (PR #208727)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/46848

<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 'Clang-Unit :: ./AllClangUnitTests/27/54' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/tools/clang/unittests/./AllClangUnitTests-Clang-Unit-69071-27-54.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=54 GTEST_SHARD_INDEX=27 /Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/tools/clang/unittests/./AllClangUnitTests
--

Note: This is test shard 28 of 54.
[==========] Running 503 tests from 101 test suites.
[----------] Global test environment set-up.
[----------] 1 test from MinimizeSourceToDependencyDirectivesTest
[ RUN      ] MinimizeSourceToDependencyDirectivesTest.Pragma
[       OK ] MinimizeSourceToDependencyDirectivesTest.Pragma (0 ms)
[----------] 1 test from MinimizeSourceToDependencyDirectivesTest (0 ms total)

[----------] 1 test from LexerTest
[ RUN      ] LexerTest.GetSourceTextExpandsToMaximumInMacroArgumentForEndOfMacro
[       OK ] LexerTest.GetSourceTextExpandsToMaximumInMacroArgumentForEndOfMacro (0 ms)
[----------] 1 test from LexerTest (0 ms total)

[----------] 1 test from PPCallbacksTest
[ RUN      ] PPCallbacksTest.QuotedInMacro
[       OK ] PPCallbacksTest.QuotedInMacro (0 ms)
[----------] 1 test from PPCallbacksTest (0 ms total)

[----------] 1 test from ParseHLSLRootSignatureTest
[ RUN      ] ParseHLSLRootSignatureTest.InvalidDescriptorTableParamTest
[       OK ] ParseHLSLRootSignatureTest.InvalidDescriptorTableParamTest (0 ms)
[----------] 1 test from ParseHLSLRootSignatureTest (0 ms total)

[----------] 1 test from ToolChainTest
[ RUN      ] ToolChainTest.ConfigFileError
[       OK ] ToolChainTest.ConfigFileError (0 ms)
[----------] 1 test from ToolChainTest (0 ms total)

[----------] 1 test from DependencyScanningWorkerFilesystem
[ RUN      ] DependencyScanningWorkerFilesystem.ConcurrentSameFilenameDeduplicates
[       OK ] DependencyScanningWorkerFilesystem.ConcurrentSameFilenameDeduplicates (1 ms)
[----------] 1 test from DependencyScanningWorkerFilesystem (1 ms total)

[----------] 2 tests from ExprMutationAnalyzerTest
[ RUN      ] ExprMutationAnalyzerTest.BindingModifies
[       OK ] ExprMutationAnalyzerTest.BindingModifies (5 ms)
[ RUN      ] ExprMutationAnalyzerTest.NotUnevaluatedExpressions
input.cc:1:19: warning: expression result unused [-Wunused-value]
    1 | void f() { int x; sizeof(int[x++]); }
      |                   ^~~~~~~~~~~~~~~~
input.cc:1:126: warning: expression with side effects will be evaluated despite being used as an operand to 'typeid' [-Wpotentially-evaluated-expression]
    1 | namespace std { class type_info; }struct A { virtual ~A(); }; struct B : A {};struct X { A& f(); }; void f() { X x; typeid(x.f()); }
      |                                                                                                                              ^
input.cc:1:117: warning: expression result unused [-Wunused-value]
...

```

</details>

https://github.com/llvm/llvm-project/pull/208727