infinite limits with units and segbuf broken

The issue is that segbufs don't always work with infinite limits, such as when the limits have units.
This is a MWE
```julia
using QuadGK, Unitful

Tu = typeof(1.0u"m")
segbuf = QuadGK.alloc_segbuf(Tu, Tu, Tu)

quadgk(x -> 1/(1+oneunit(x)/x), 0.0u"m", 1.0u"m", segbuf=segbuf) # OK (0.3068528194400547 m, 1.9931833961095435e-11 m)

quadgk(x -> 1/(1+oneunit(x)/x), 0.0u"m", Inf*u"m", segbuf=segbuf) # broken
```
which gives the error
```julia
ERROR: DimensionError: m and 0.0 are not dimensionally compatible.
Stacktrace:
[1] convert(#unused#::Type{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}, x::Float64)
@ Unitful ~/.julia/packages/Unitful/jiUeO/src/conversion.jl:106
[2] QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}(a::Float64, b::Float64, I::Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, E::Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}})
@ QuadGK ~/.julia/dev/QuadGK/src/evalrule.jl:3
[3] convert(#unused#::Type{QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}, s::QuadGK.Segment{Float64, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}})
@ QuadGK ~/.julia/dev/QuadGK/src/evalrule.jl:10
[4] setindex!(A::Vector{QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}, x::QuadGK.Segment{Float64, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}, i1::Int64)
@ Base ./array.jl:969
[5] macro expansion
@ ./broadcast.jl:974 [inlined]
[6] macro expansion
@ ./simdloop.jl:77 [inlined]
[7] copyto!
@ ./broadcast.jl:973 [inlined]
[8] copyto!
@ ./broadcast.jl:926 [inlined]
[9] materialize!
@ ./broadcast.jl:884 [inlined]
[10] materialize!
@ ./broadcast.jl:881 [inlined]
[11] do_quadgk(f::QuadGK.var"#18#27"{var"#11#12", Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}, s::Tuple{Float64, Float64}, n::Int64, atol::Nothing, rtol::Nothing, maxevals::Int64, nrm::typeof(LinearAlgebra.norm), segbuf::Vector{QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}})
@ QuadGK ~/.julia/dev/QuadGK/src/adapt.jl:39
[12] #50
@ ~/.julia/dev/QuadGK/src/adapt.jl:235 [inlined]
[13] handle_infinities(workfunc::QuadGK.var"#50#51"{Nothing, Nothing, Int64, Int64, typeof(LinearAlgebra.norm), Vector{QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}}}, f::var"#11#12", s::Tuple{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}})
@ QuadGK ~/.julia/dev/QuadGK/src/adapt.jl:126
[14] quadgk(::Function, ::Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, ::Vararg{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}; atol::Nothing, rtol::Nothing, maxevals::Int64, order::Int64, norm::Function, segbuf::Vector{QuadGK.Segment{Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}, Quantity{Float64, 𝐋, Unitful.FreeUnits{(m,), 𝐋, nothing}}}})
@ QuadGK ~/.julia/dev/QuadGK/src/adapt.jl:234
[15] top-level scope
@ REPL[11]:1
```