[clang] [llvm] [CHERI][RISCV][AArch64][MC] Add shared support for aligning globals to an "alignment granule", which is applied to both the alignment and the allocated size. (PR #203872)

[Owen Anderson via cfe-commits]

resistor wrote:

> This looks much cleaner to me now, and it sounds like @jrtc27 is happy with using the padded st_size, so I think we should go for this approach.
> 
> Commit title needs to also mention AArch64+MTE, or it could be landed in two PRs?

Squashed, rebased, updated commit message and PR description.

https://github.com/llvm/llvm-project/pull/203872