[clang] [ClangOffloadBundler] Add file size to header (PR #88827)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 commented:

Isn't this ABI breaking since we're changing the size of the struct? Shouldn't that necessitate a new version?

Also unrelated, I wonder if there's a future where we can use the ClangOffloadPackager format in the HIP runtime.

https://github.com/llvm/llvm-project/pull/88827