[clang] [llvm] [Clang-Repl] Add support for out-of-process execution. (PR #110418)

[LLVM Continuous Integration via llvm-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/7335

<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 :: Interpreter/out-of-process.cpp' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 3: cat /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Interpreter/out-of-process.cpp | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang-repl -oop-executor -orc-runtime | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Interpreter/out-of-process.cpp
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang-repl -oop-executor -orc-runtime
+ cat /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Interpreter/out-of-process.cpp
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Interpreter/out-of-process.cpp
clang-repl: No such file or directory
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/Interpreter/out-of-process.cpp

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/110418