OS/2 sTypoDescender should be -ve not positive, and the hhea and OS/2
values should agree. Also OS/2 usWinAscent/Descent should be big enough
for any glyph in the font.

Change-Id: Iad201f268f4e030565795e858a5a42937328ec80
Reviewed-on: https://gerrit.libreoffice.org/31060Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Khaled Hosny <khaledhosny@eglug.org>