[clang] [clang-repl] Extend the C support. (PR #89804)

[Jason Molenda via cfe-commits]

jasonmolenda wrote:

I set aside my current work, updated to current main sources, cherry-picked 253c28fa829cee0104c2fc59ed1a958980b5138c, built it on my macOS system, did `bin/lldb-dotest -p TestImportBuiltinFileID.py` and it crashes like before.

I'm not sure what you're asking help with, I don't know much of anything about how the clang setup in lldb is done - I happened to be watching the CI bots and saw they all started failing and reverted the change.  

You couldn't reproduce this behavior on a macOS system?  it is an arm64 macOS system, I didn't try repo'ing on an Intel box.  

Earlier on this PR you mused about making this change in SemaDecl.cpp

```
-    if (!PP.isIncrementalProcessingEnabled())
+    if (!PP.isIncrementalProcessingEnabled() && !getLangOpts().IncrementalExtensions)
```

the test case still crashes for me with that change.

https://github.com/llvm/llvm-project/pull/89804