[clang] [CIR] Implement NRVO variable cleanup (PR #170774)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

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

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/32291

<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/5/14' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests-LLVM-Unit-23435-5-14.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=14 GTEST_SHARD_INDEX=5 /Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests
--

Script:
--
/Volumes/RAMDisk/buildbot-root/aarch64-darwin/build/unittests/Support/./SupportTests --gtest_filter=FileSystemTest.permissions
--
Test Directory: /tmp/lit-tmp-2hbnmzme/file-system-test-a5f4ca
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2359: Failure
Value of: CheckPermissions(fs::set_gid_on_exe)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2374: Failure
Value of: CheckPermissions(fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2381: Failure
Value of: CheckPermissions(fs::all_read | fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2384: Failure
Value of: CheckPermissions(fs::all_perms)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2389: Failure
Value of: CheckPermissions(fs::all_perms & ~fs::sticky_bit)
  Actual: false
Expected: true


/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2359
Value of: CheckPermissions(fs::set_gid_on_exe)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2374
Value of: CheckPermissions(fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
Expected: true

/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/llvm/unittests/Support/Path.cpp:2381
Value of: CheckPermissions(fs::all_read | fs::set_uid_on_exe | fs::set_gid_on_exe | fs::sticky_bit)
  Actual: false
...

```

</details>

https://github.com/llvm/llvm-project/pull/170774