[IR] Make optnone imply noinline (#228169)
Previously the verifier required every `optnone` function to also carry
`noinline`. Instead, make `optnone` imply `noinline` so the pairing is
no
longer necessary.
To avoid each user having to remember to check both attributes, add
`Function::isNoInline()` (true for `noinline` or `optnone`) and make
`CallBase::isNoInline()` defer to it for the callee. Existing direct
queries of `Attribute::NoInline` on functions are migrated to the
helper.
The verifier now explicitly rejects `alwaysinline` + `optnone`, which
was
previously only enforced transitively via the `noinline` requirement.
ForceFunctionAttrs and llvm-reduce no longer need to keep the two
attributes paired.
Assisted-By: Claude
