[clang] Reapply "[Clang] [NFC] Introduce a helper for emitting compatibility diagnostics (#132348)" (PR #134043)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vla` running on `linaro-g3-04` while building `clang` at step 7 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/17/builds/6958

<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)
...
PASS: Flang :: Driver/predefined-macros-x86.f90 (25187 of 97579)
PASS: Flang :: Driver/bbc-openmp-version-macro.f90 (25188 of 97579)
PASS: Clangd Unit Tests :: ./ClangdTests/75/81 (25189 of 97579)
PASS: Flang :: Driver/phases.f90 (25190 of 97579)
PASS: Flang :: Driver/macro-def-undef.F90 (25191 of 97579)
PASS: Flang :: Driver/override-triple.ll (25192 of 97579)
PASS: Flang :: Driver/print-effective-triple.f90 (25193 of 97579)
PASS: Flang :: Driver/print-resource-dir.F90 (25194 of 97579)
PASS: Flang :: Driver/mlink-builtin-bc.f90 (25195 of 97579)
UNRESOLVED: Flang :: Driver/slp-vectorize.ll (25196 of 97579)
******************** TEST 'Flang :: Driver/slp-vectorize.ll' FAILED ********************
Test has no 'RUN:' line
********************
PASS: Flang :: Driver/predefined-macros-compiler-version.F90 (25197 of 97579)
PASS: Flang :: Driver/parse-fir-error.ll (25198 of 97579)
PASS: Flang :: Driver/parse-error.ll (25199 of 97579)
PASS: Flang :: Driver/mlir-pass-pipeline.f90 (25200 of 97579)
PASS: Flang :: Driver/fd-lines-as.f90 (25201 of 97579)
PASS: Flang :: Driver/include-header.f90 (25202 of 97579)
PASS: Flang :: Driver/linker-flags.f90 (25203 of 97579)
PASS: Flang :: Driver/parse-ir-error.f95 (25204 of 97579)
PASS: Flang :: Driver/print-target-triple.f90 (25205 of 97579)
PASS: Flang :: Driver/pass-plugin-not-found.f90 (25206 of 97579)
PASS: Flang :: Driver/pthread.f90 (25207 of 97579)
PASS: Flang :: Driver/print-pipeline-passes.f90 (25208 of 97579)
PASS: Flang :: Driver/missing-arg.f90 (25209 of 97579)
PASS: Flang :: Driver/scanning-error.f95 (25210 of 97579)
PASS: Clangd Unit Tests :: ./ClangdTests/80/81 (25211 of 97579)
PASS: Flang :: Driver/lto-bc.f90 (25212 of 97579)
PASS: Flang :: Driver/std2018-wrong.f90 (25213 of 97579)
PASS: Flang :: Driver/supported-suffices/f08-suffix.f08 (25214 of 97579)
PASS: Flang :: Driver/supported-suffices/f03-suffix.f03 (25215 of 97579)
PASS: Flang :: Driver/config-file.f90 (25216 of 97579)
PASS: Flang :: Driver/tco-code-gen-llvm.fir (25217 of 97579)
PASS: Flang :: Driver/target.f90 (25218 of 97579)
PASS: Flang :: Driver/target-gpu-features.f90 (25219 of 97579)
PASS: Flang :: Driver/pp-fixed-form.f90 (25220 of 97579)
PASS: Clangd Unit Tests :: ./ClangdTests/68/81 (25221 of 97579)
PASS: Flang :: Driver/multiple-input-files.f90 (25222 of 97579)
PASS: Flang :: Driver/q-unused-arguments.f90 (25223 of 97579)
PASS: Flang :: Driver/unsupported-vscale-max-min.f90 (25224 of 97579)
PASS: Clangd Unit Tests :: ./ClangdTests/71/81 (25225 of 97579)
PASS: Flang :: Driver/fsave-optimization-record.f90 (25226 of 97579)
PASS: Flang :: Driver/no-duplicate-main.f90 (25227 of 97579)
PASS: Flang :: Driver/unparse-with-modules.f90 (25228 of 97579)
PASS: Flang :: Driver/mllvm.f90 (25229 of 97579)
PASS: Flang :: Driver/lto-flags.f90 (25230 of 97579)
PASS: Flang :: Driver/target-machine-error.f90 (25231 of 97579)
PASS: Flang :: Driver/input-from-stdin/input-from-stdin.f90 (25232 of 97579)

```

</details>

https://github.com/llvm/llvm-project/pull/134043