[clang] [clang] Add FixItHint for designated init order (PR #173136)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `sanitizer-windows` running on `sanitizer-windows` while building `clang` at step 7 "test-build-unified-tree-check-compiler-rt".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/107/builds/16228

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

```
Step 7 (test-build-unified-tree-check-compiler-rt) failure: test (failure)
******************** TEST 'SanitizerCommon-Unit :: ./Sanitizer-x86_64-Test.exe/18/22' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:C:\b\slave\sanitizer-windows\build\runtimes\runtimes-bins\compiler-rt\lib\sanitizer_common\tests\.\Sanitizer-x86_64-Test.exe-SanitizerCommon-Unit-7896-18-22.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=22 GTEST_SHARD_INDEX=18 C:\b\slave\sanitizer-windows\build\runtimes\runtimes-bins\compiler-rt\lib\sanitizer_common\tests\.\Sanitizer-x86_64-Test.exe
--

Script:
--
C:\b\slave\sanitizer-windows\build\runtimes\runtimes-bins\compiler-rt\lib\sanitizer_common\tests\.\Sanitizer-x86_64-Test.exe --gtest_filter=StopTheWorld.SuspendThreadsAdvanced
--
C:/b/slave/sanitizer-windows/llvm-project/compiler-rt/lib/sanitizer_common/tests/sanitizer_stoptheworld_test.cpp(144): error: Value of: argument.threads_stopped
  Actual: false
Expected: true


C:/b/slave/sanitizer-windows/llvm-project/compiler-rt/lib/sanitizer_common/tests/sanitizer_stoptheworld_test.cpp:144
Value of: argument.threads_stopped
  Actual: false
Expected: true



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


```

</details>

https://github.com/llvm/llvm-project/pull/173136