Footnotes inside header markups

[Barikavily]

> I'm not top posting.

\version "2.16.2"

% Footnotes don't work when located inside a header block
% (Same thing happens with auto-footnote)

\markup { 
        Top-level markup
        \footnote "*" \italic "* This is my top-level markup footnote" 
}

\score {
        { c' }
        \header {
                piece = \markup { 
                        Piece markup
                        \footnote "**" \italic "** Footnote about the piece 
title"  
                }
        }
}