[clang] [clang-repl] Skip tests for non-linux and non-darwin platforms from #152562 (PR #153005)

[Rainer Orth via cfe-commits]

rorth wrote:

(Some commenting the code directly didn't work for me ;-)

This check
```
!SystemTriple.isOSLinux()
```
isn't enough: it encompasses any version of Linux, not just Linux/x86_64.  Besides, as I said, `getOrcRuntimePath` currently hardcodes the `runtimes` layout while one can still use the `projects` layout if one so chooses.  I'd rather you'd skip the test unconditionally until this is all figured out: as is, the cost is way too fragile and makes many unwarranted assumptions.

https://github.com/llvm/llvm-project/pull/153005