[FriBidi] fribidi_reorder_runs()

[Eli Zaretskii]

> From: Eduardo Castiñeyra <eduardo at brainstorm3d.com>
> Date: Tue, 7 Feb 2017 16:39:01 +0100
> 
> It turned out that our incorrect way to integrate fribidi and harfbuzz 
> (let fribidi reorder all the characters and shape as full LTR in 
> harfbuzz) is "surprisingly" causing problems.
> 
> The problem is mainly with the parenthesis. It looks like the shaper 
> should flip the direction of the parenthesis when it belongs to a RTL run.

Shouldn't reordering mirror parentheses if their level is even?