Fix error in cglobal expressions created by macro with escaped literals

[jmert]

In #26297 (#issuecomment-371165725), I made reference to a problem with cglobal expressions created by macros — as PyCall uses — on master. This PR is a [naive] attempt at fixing that issue (which I think ends up being distinct from the original error being reported in #26297).

I don't actually know lisp so this is mostly just guessing, but some time spent with git grep and combinations of @code_lowered and Meta.expand(), I maybe lucked in to a solution.

With this (plus a lot of patience — see #26357) I was actually able to get a PyPlot window to show on master!

Before:

julia> @code_typed cglobal26297()
CodeInfo(:(begin
      Core.SSAValue(0) = (Core.tuple)(:global_var, "libccalltest")::Tuple{Symbol,String}
      Core.SSAValue(1) = (Main.cglobal)(Core.SSAValue(0), Main.Cint)::Ptr{Int32}
      return Core.SSAValue(1)
  end)) => Ptr{Int32}

After:

julia> @code_typed cglobal26297()
CodeInfo(:(begin 
        return (Main.cglobal)((Core.tuple)(:global_var, "libccalltest")::Tuple{Symbol,String}, Main.Cint)::Ptr{Int32}
    end))=>Ptr{Int32}

[vtjnash]

no quotes around libccalltest (it's a variable at the top of this file)

[stevengj]

CI failures seem unrelated...