inlining: add missing late special handling for `UnionAll` method call (#43479)
Looking at the result of <https://github.com/JuliaLang/julia/issues/43452#issuecomment-996971256>,
I found that currently the inlinear sometimes fails to handle `UnionAll`
call (e.g. runtime dispatch detected: Core.UnionAll(%28::TypeVar, %29::Any)).
This commit adds a missing late special handling for `UnionAll` calls:
> before
```julia
julia> code_typed((TypeVar,)) do tv
UnionAll(tv, Type{tv})
end
1-element Vector{Any}:
CodeInfo(
1 ─ %1 = Core.apply_type(Main.Type, tv)::Type{Type{_A}} where _A
│ %2 = Main.UnionAll(tv, %1)::Any
└── return %2
) => Any
```
> after
```julia
julia> code_typed((TypeVar,)) do tv
UnionAll(tv, Type{tv})
end
1-element Vector{Any}:
CodeInfo(
1 ─ %1 = Core.apply_type(Main.Type, tv)::Type{Type{_A}} where _A
│ %2 = $(Expr(:foreigncall, :(:jl_type_unionall), Any, svec(Any, Any), 0, :(:ccall), Core.Argument(2), :(%1)))::Any
└── return %2
) => Any
```
julia
fb3ee73e - inlining: add missing late special handling for `UnionAll` method call (#43479)
