This is only used in conjunction with SalLayout::GetNextGlyphs() in
vcl/source/gdi/pdfwriter_impl.cxx to retrieve the fallback font, if any,
used to layout the given glyph, but it is a very convoluted way to do a
straight forward thing, and hard to adapt for new SalLayout
implementations.

So now I just pass a fallback fonts array, when requested, in
GetNextGlyphs() itself.

Change-Id: I24e7931f64867a4fb4e7b728c65faa6198e24aba
Reviewed-on: https://gerrit.libreoffice.org/4285Reviewed-by: Khaled Hosny <khaledhosny@eglug.org>
Tested-by: Khaled Hosny <khaledhosny@eglug.org>