fix a bug preventing inlining of getindex of const globals

[JeffBezanson]

For example

julia> const k = [1];

julia> f() = k[1];

julia> @code_typed f()
CodeInfo(
1 ─ %1 = invoke Base.getindex(Main.k::Array{Int64,1}, 1::Int64)::Int64
└──      return %1
) => Int64

Fixes #31460