[clang] [CIR] Emit trailing-zero array constants as a compact split (PR #205918)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

This seems to have gotten even more complex?  It seems odd that this is necessary here.  Can we stop back and make sure this is all required?  For example, in the array lowering it appears you do this trailing-zero lowering bits like 3x?  

And also, why does this touch ExprConstant.cpp? 

https://github.com/llvm/llvm-project/pull/205918