[llvm] Solve llvm-dwp overflow problem, skipped over 4GB '.dwo' files (PR #71902)

[David Blaikie via llvm-commits]

dwblaikie wrote:

> When 'ContinueOnCuIndexOverflow' enables without this modification, the forcibly generated '.dwp' won't be recognized by Debugger correctly.

The whole point of the `ContinueOnCuIndexOverflow` is to continue(& allow tools like llvm-dwarfdump and lldb to continue with this corrupted index by reconstructing the .debug_info column in the DWP despite the overflow, by parsing the .debug_info section to find the boundary points/rebuild that column in the index) so this patch wouldn't be compatible with that goal.

We could add another flag that is sort of "best effort" DWP that emits a correct one with as many CUs as it can... but that doesn't seem /super/ useful?

@ayermolo 

https://github.com/llvm/llvm-project/pull/71902