Rollup merge of #40521 - TimNN:panic-free-shift, r=alexcrichton

Implemente overflowing_sh* with new unchecked_sh* intrinsics

Also update some 128 bit builtins to not rely on the constant evaluator to avoid checked operations.

Fixes #40508.

cc @nagisa, @alexcrichton

Note: I still have a build running to see if the 128 bit changes worked (unoptimized builds take *forever* to compile), however at least the overflowing builtins no longer reference `core::panicking::panic`.

diff --cc src/libcore/num/mod.rs
Simple merge