[clang] [clang] LazyOffsetPtr: Use native pointer width (PR #111995)

[A. Wilcox via cfe-commits]

awilfox wrote:

This patch has been tested on 32-bit PowerPC, 64-bit PowerPC, and 64-bit x86_64 (ensuring it doesn't change any behaviour on LE systems) - the entire Clang test suite passed on all three platforms.

https://github.com/llvm/llvm-project/pull/111995