[clang] [clang] Convert second arg of __builtin_assume_aligned to ConstantExpr (PR #161314)

[Alan Zhao via cfe-commits]

alanzhao1 wrote:

> Heads up - this PR is causing us to hit the following assertion in https://github.com/google/highway. I'm currently running cvise to get a minimal reproducer.

The repro file is 2.5M, so cvise will take forever. This will take a while, so I apologize in advance.

https://github.com/llvm/llvm-project/pull/161314