OSX: Disable window restoration for the Mac font panel

OSX: Disable window restoration for the Mac font panel

because if it is automatically restored it's out of the application's
control, so the user's interaction will be ignored.  Change
I8ce3cd94f5ae81d7877a346743ca4e0e188baa02 did this for normal windows
by default, but the dialog helpers generate windows which aren't
affected by that.

Change-Id: I46ce3f85ee0c11dca778eb663c87774e322d6b6b
(cherry-picked from qtbase commit c9182bc11b77675405941a0a163603cac064d8bc)
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>