[llvm] [Hexagon] Disable restore stubs when ShadowCallStack is active (PR #206302)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `libc-x86_64-debian-fullbuild-dbg` running on `libc-x86_64-debian-fullbuild` while building `llvm` at step 3 "checkout".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/179/builds/49667

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

```
Step 3 (checkout) failure: update (failure)
git version 2.39.5
error: RPC failed; HTTP 429 curl 22 The requested URL returned error: 429
fatal: expected 'acknowledgments'
remote: This request was rate-limited due to too many requests. Reduce the frequency of your requests or try again later.
remote: For more on scraping GitHub and how it may affect your rights, please review our Terms of Service (https://docs.github.com/en/site-policy/github-terms/github-terms-of-service).
fatal: unable to access 'https://github.com/llvm/llvm-project.git/': The requested URL returned error: 429

```

</details>

https://github.com/llvm/llvm-project/pull/206302