[clang] [clang-repl] Simplify the logic around out of process execution. NFC (PR #175322)

[via cfe-commits]

HighW4y2H3ll wrote:

> Do you know where your or runtime is? Looks like it is not anywhere in:
> 
> ```
> [ RUN      ] OutOfProcessInterpreterTest.FindRuntimeInterface
> Failure value returned from cantFail wrapped call
> OrcRuntime library not found. Checked:
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/unittests/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/unittests/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/unittests/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/unittests/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/clang/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/tools/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/solaris11-amd64/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/home/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/home/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/llvm-buildbot/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/llvm-buildbot/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /opt/lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /opt/lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
>   /lib/clang/23/lib/amd64-pc-solaris2.11/libclang_rt.orc_rt.a
>   /lib/clang/23/lib/amd64-pc-solaris2.11/liborc_rt.a
> UNREACHABLE executed at /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/llvm/llvm/include/llvm/Support/Error.h:810!
> ```

Hi, this PR also breaks our X86 build in clang unittests when orc runtime cannot be found. It seem to be failing at the `cantFail` here: https://github.com/llvm/llvm-project/blob/main/clang/unittests/Interpreter/OutOfProcessInterpreterTests.cpp#L167 Is this https://github.com/llvm/llvm-project/pull/176198 supposed to fix it?

https://github.com/llvm/llvm-project/pull/175322