[clang] clang/AMDGPU: Add missing field to implicit kernarg struct definition (PR #185209)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-darwin` running on `doug-worker-3` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/23/builds/18377

<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/10/14' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/unittests/Support/./SupportTests-LLVM-Unit-37962-10-14.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=14 GTEST_SHARD_INDEX=10 /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/unittests/Support/./SupportTests
--

Note: This is test shard 11 of 14.
[==========] Running 121 tests from 85 test suites.
[----------] Global test environment set-up.
[----------] 2 tests from AlignmentTest
[ RUN      ] AlignmentTest.AlignConstant
[       OK ] AlignmentTest.AlignConstant (0 ms)
[ RUN      ] AlignmentTest.AlignComparisons
[       OK ] AlignmentTest.AlignComparisons (0 ms)
[----------] 2 tests from AlignmentTest (0 ms total)

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

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

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

[----------] 2 tests from BinaryStreamTest
[ RUN      ] BinaryStreamTest.MutableBinaryByteStreamBounds
[       OK ] BinaryStreamTest.MutableBinaryByteStreamBounds (0 ms)
[ RUN      ] BinaryStreamTest.StreamWriterIntegerArrays
[       OK ] BinaryStreamTest.StreamWriterIntegerArrays (0 ms)
[----------] 2 tests from BinaryStreamTest (0 ms total)

[----------] 1 test from BlockFrequencyTest
[ RUN      ] BlockFrequencyTest.Saturate
[       OK ] BlockFrequencyTest.Saturate (0 ms)
[----------] 1 test from BlockFrequencyTest (0 ms total)

[----------] 1 test from BranchProbabilityTest
[ RUN      ] BranchProbabilityTest.NormalizeProbabilities
[       OK ] BranchProbabilityTest.NormalizeProbabilities (0 ms)
[----------] 1 test from BranchProbabilityTest (0 ms total)

[----------] 1 test from Caching
[ RUN      ] Caching.WriteAfterCommit
...

```

</details>

https://github.com/llvm/llvm-project/pull/185209