[llvm] Reland "Add a pass to collect dropped var stats for MIR" (PR #117044)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-win-fast` running on `as-builder-3` while building `llvm` at step 7 "test-build-unified-tree-check-llvm-unit".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/2/builds/12361

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

```
Step 7 (test-build-unified-tree-check-llvm-unit) failure: test (failure)
******************** TEST 'LLVM-Unit :: CodeGen/./CodeGenTests.exe/20/75' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\CodeGen\.\CodeGenTests.exe-LLVM-Unit-9308-20-75.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=75 GTEST_SHARD_INDEX=20 C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\CodeGen\.\CodeGenTests.exe
--

Script:
--
C:\buildbot\as-builder-3\llvm-clang-x86_64-win-fast\build\unittests\CodeGen\.\CodeGenTests.exe --gtest_filter=DroppedVariableStatsMIR.DbgValLost
--
unknown file: error: SEH exception with code 0x3221225477 thrown in the test body.
Stack trace:



unknown file
SEH exception with code 0x3221225477 thrown in the test body.
Stack trace:




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


```

</details>

https://github.com/llvm/llvm-project/pull/117044