[clang] [Clang] Reuse tail-padding for more types that are not POD for the purpose of layout (PR #90462)

[Mital Ashok via cfe-commits]

MitalAshok wrote:

I have reached out to Fuschia on their discord and am still waiting for a response.  
I was unable to find a place to ask someone related to IBM XL what is supposed to happen (and I couldn't get the xl++ compiler to check what it does). Would be grateful if someone more knowledgeable about this could help.

This patch currently changes nothing for Fuschia and XL. It could be merged as is and the Fuschia/XL behaviour could be changed for -fclang-abi-compat=20 if they need to be changed. Or this could be pushed back entirely for Clang 20

https://github.com/llvm/llvm-project/pull/90462