[clang] [clang][bytecode] Check for invalid record decls in IntPointer::atOffset (PR #169786)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-armv8-quick` running on `linaro-clang-armv8-quick` while building `clang` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/24509

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clang :: AST/ByteCode/invalid.cpp' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/22/include -nostdsysteminc -fcxx-exceptions -std=c++20 -fexperimental-new-constant-interpreter -verify=expected,both /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/invalid.cpp
# executed command: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/22/include -nostdsysteminc -fcxx-exceptions -std=c++20 -fexperimental-new-constant-interpreter -verify=expected,both /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/invalid.cpp
# .---command stderr------------
# | error: diagnostics with 'error' severity expected but not seen: 
# |   File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/invalid.cpp Line 121 'both-error': array is too large
# | 1 error generated.
# `-----------------------------
# error: command failed with exit status: 1

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/169786