[clang] [clang-repl] Pass triple to IncrementalCompilerBuilder as explicit argument (PR #84174)

[Stefan Gränitz via cfe-commits]

weliveindetail wrote:

Interesting, thanks for reporting! It's this code:
```
  llvm::MemoryBuffer *MB = llvm::MemoryBuffer::getMemBuffer("").release();
  Clang->getPreprocessorOpts().addRemappedFile("<<< inputs >>>", MB);
```

Apparently, it is related to releasing the MemBuffer and passing the raw pointer to `addRemappedFile()`, but I don't see why this fails here and not in any of the existing tests. Let me revert and investigate tomorrow.

https://github.com/llvm/llvm-project/pull/84174