[5/9] gdiplus: Fix empty glyph handling.

[Vincent Povirk]

This seems suspicious to me. Why can't we use those values in
glyphmetrics if GetGlyphOutlineW returns 0? Does Windows provide bad
values in this case, or is our GetGlyphOutlineW broken? When does the
call to GetGlyphOutlineW in the second loop fail, and why ignore those
failures?