[clang] [ExprConstant] Handle shift overflow the same way as other kinds of overflow (PR #99579)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Filed #99680 and #99684 for issues caused by custom codepaths for evaluating ICEs.  Hopefully we can improve that at some point.

https://github.com/llvm/llvm-project/pull/99579