[LLDB][PDB] Warn if DIA plugin is requested but not available (#160067)
If LLDB was built without the DIA SDK and the DIA reader is explicitly
requested (through `LLDB_USE_NATIVE_PDB_READER=0` or `settings set
plugin.symbol-file.pdb.reader dia`), LLDB should print a warning,
because it will use the native reader in any case
(https://github.com/llvm/llvm-project/pull/159769#discussion_r2367316980).
This PR adds the warning and a test when LLDB is not built with the SDK
on Windows. I don't think any builder runs this configuration, as there
are still five failing tests. I tested this locally with and without the
SDK.
GitOrigin-RevId: 5b3dd43bd20d9c4e1cd05e39d2e022b368b0fbdc
3 files changed