bug#11860: 24.1; Arabic - Harakat (diacritics, short vowels) don't appear

[Eli Zaretskii]

> From: Steffan <smias@yandex.ru>
> Cc: smias@yandex.ru,jasonr@gnu.org,11860@debbugs.gnu.org,Kenichi Handa 
> <handa@gnu.org>
> Date: Mon, 03 Sep 2012 17:31:39 +0200
> 
> Thanks, this bug is now fixed. But there is something wrong with the two 
> diacritics (short vowels): ARABIC KASRA and ARABIC KASRATAN. They should 
> appear UNDER the letters, not IN or OVER them.
> 
> Try a-A [Sheen-Kasra] or a-S [Sheen-Kasratan] or d-S [Ya-Kasratan]. 
> But h-S or m-S has the correct form. (?)

This happened because w32uniscribe.c didn't reverse the sign of the
y-offsets returned by the Uniscribe shaper.  This reversal is
necessary because the Y axes in font definition coordinates and in
Emacs screen coordinates point in opposite directions.

I see that ftfont.c consistently reverses the sign of y-offsets,
probably for the same reason.

Fixed in trunk revision 109876.  Please test.

P.S. This bug affected all complex scripts, not just RTL or Arabic.