DPI fix in xfsettings and xfce4-settings

[Jannis Pohlmann]

Hey all,

I don't know if this is the final solution but I just committed a fix
to xfsettingsd and xfce4-settings for a DPI problem I spotted.

Let's assume the DPI value set by the user is 96. 

Old state: xfce4-settings/appearance-settings/main.c saves 96 * 1024 to
xfconfd and xfsettingsd receives 96 * 1024 as DPI value and passes it
to both, xrdb and X (via an XChangeProperty call). Now xrdb has this
very high value and a lot of apps are broken (like any application that
uses Qt3 or Qt4).

New state: xfce4-settings/appearance-settings/main.c saves 94 to
xfconfd and xfsettingsd receives 96. It passes 96 to xrdb and 94 * 1024
to X (again via XChangeProperty). Now everything works.

However, this is critical: Please make sure that you have a
realistic value (something between 50 and 150) in the '/Xft/DPI'
property in ~/.config/xfce4/xfconf/xfce-perchannel-xml/xsettings.xml.
Otherwise you might encounter serious problems!

  - Jannis