[clang] [lldb] [clang][RecordLayoutBuilder] Be stricter about inferring packed-ness in ExternalLayouts (PR #97443)

[Pavel Labath via cfe-commits]

labath wrote:

> Skipping empty fields does seem like a better heuristic here

FWIW, I (independently) came to the same conclusion when investigating the fallout of  #76756, though it's not fully clear to me whether the PR has been updated to do that.

https://github.com/llvm/llvm-project/pull/97443