[clang] [clang][CGRecordLayout] Remove dependency on isZeroSize (PR #96422)

[Reid Kleckner via cfe-commits]

rnk wrote:

IIUC, this effectively removes all empty records from LLVM struct types. This makes the IR less "pretty", but these subobjects are notionally empty and consist of only padding bytes (i8 and i8 arrays) at the end of the day. I think that's acceptable. + @rjmccall , does that sound good to you?

https://github.com/llvm/llvm-project/pull/96422