Missing coverage for macros that add new lines

[bramtayl]

Macros that add new lines do not seem to be being tracked properly by coverage. Consider the following example:

macro adds_more_lines()
    quote
        "code"
    end
end

function add_more_lines()
    @add_more_lines
end

add_more_lines()

If a user runs this code, one would expect all lines to show up as covered. However, the line inside the function does not seem to be showing up as covered. See JuliaAudio/PortAudio.jl#76 for an example.