[llvm] [SandboxVec] Add region-from-bbs helper pass (PR #130153)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `premerge-monolithic-linux` running on `premerge-linux-1` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/153/builds/25119

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

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM-Unit :: Support/./SupportTests/48/88' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/build/buildbot/premerge-monolithic-linux/build/unittests/Support/./SupportTests-LLVM-Unit-1190634-48-88.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=88 GTEST_SHARD_INDEX=48 /build/buildbot/premerge-monolithic-linux/build/unittests/Support/./SupportTests
--

Script:
--
/build/buildbot/premerge-monolithic-linux/build/unittests/Support/./SupportTests --gtest_filter=Caching.NoCommit
--
/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/Support/Caching.cpp:149: Failure
Value of: llvm::detail::TakeError(CFS->commit())
Expected: succeeded
  Actual: failed  (Failed to rename temporary file /tmp/lit-tmp-7cdk8696/llvm_test_cache/LLVMTest-667add.tmp.o to /tmp/lit-tmp-7cdk8696/llvm_test_cache/llvmcache-foo: No such file or directory
)


/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/Support/Caching.cpp:149
Value of: llvm::detail::TakeError(CFS->commit())
Expected: succeeded
  Actual: failed  (Failed to rename temporary file /tmp/lit-tmp-7cdk8696/llvm_test_cache/LLVMTest-667add.tmp.o to /tmp/lit-tmp-7cdk8696/llvm_test_cache/llvmcache-foo: No such file or directory
)



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


```

</details>

https://github.com/llvm/llvm-project/pull/130153