[clang] [LifetimeSafety] Fix use-after-scope from #198784 (PR #199455)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vls` running on `linaro-g3-01` while building `clang` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/143/builds/15407

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'MLIR :: Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 8
/home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/bin/mlir-opt /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/llvm/mlir/test/Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir -transform-interpreter -test-transform-dialect-erase-schedule -cse -canonicalize -test-lower-to-llvm | mlir-runner -e main -entry-point-result=void --march=aarch64 --mattr="+sve" -shared-libs=/home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/lib/libmlir_runner_utils.so,/home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/lib/libmlir_c_runner_utils.so | /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/llvm/mlir/test/Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/bin/mlir-opt /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/llvm/mlir/test/Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir -transform-interpreter -test-transform-dialect-erase-schedule -cse -canonicalize -test-lower-to-llvm
# executed command: mlir-runner -e main -entry-point-result=void --march=aarch64 --mattr=+sve -shared-libs=/home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/lib/libmlir_runner_utils.so,/home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/lib/libmlir_c_runner_utils.so
# .---command stderr------------
# | loc("<stdin>":1821:12): error: Dialect `vector' not found for custom op 'vector.shape_cast' 
# | could not parse the input IR
# `-----------------------------
# error: command failed with exit status: 1
# executed command: /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/llvm/mlir/test/Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve-vls/llvm/mlir/test/Integration/Dialect/Linalg/CPU/ArmSVE/pack-unpack-mmt4d.mlir
# `-----------------------------
# error: command failed with exit status: 2

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/199455