[clang] [llvm] [Clang] Fix definition of layout-compatible to ignore empty classes (PR #92103)

[Mital Ashok via llvm-commits]

MitalAshok wrote:

https://github.com/llvm/llvm-project/blob/b0ae923ada836fa2c9114ac2c5afb39466f49fe0/clang/docs/ReleaseNotes.rst#L210-L212

Should be enough for ReleaseNotes, since not much has changed since Clang 18

https://github.com/llvm/llvm-project/pull/92103