[clang-tools-extra] [include-cleaner] Handle non-self-contained includes. (PR #185495)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Linux-->
# :penguin: Linux x64 Test Results

* 3164 tests passed
* 7 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### clangIncludeCleaner Unit Tests
<details>
<summary>clangIncludeCleaner Unit Tests._/ClangIncludeCleanerTests/RecordASTTest/ImplicitTemplates</summary>

```
Script:
--
/home/gha/actions-runner/_work/llvm-project/llvm-project/build/tools/clang/tools/extra/include-cleaner/unittests/./ClangIncludeCleanerTests --gtest_filter=RecordASTTest.ImplicitTemplates
--
/home/gha/actions-runner/_work/llvm-project/llvm-project/clang-tools-extra/include-cleaner/unittests/RecordTest.cpp:163
Value of: Recorded.Roots
Expected: has 2 elements where
element #0 named (N: "MyGetter"),
element #1 named (N: "v")
  Actual: { 0x189d0cb0, 0x189d1130, 0x189d1398, 0x189f3860 }, which has 4 elements


```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/185495