Ports Qt5 commit: Make sure QIconLoader is always initialized

Port of Qt5 commit aa5f70c00a88edcddd26e8fea767a40e8c5c31b8

Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
Adds Qt5 QIconLoader for the Qt5 build

The Qt5 versions of QIcon and QIconLoader fixed some of the Qt4 problems.
But... some are note:
    * xpm icon support;
    * Search icons in /usr/share/pixmaps as xdg standard states.

Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
Adds xpm icon support

Copied from the old QIconLoader.

Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
Honors /usr/share/pixmaps when searching for icons.

Author: Kaitlin Rupert <kaitlin.rupert@intel.com>
 Date: Aug 12, 2010
 Description: Make it so that the QIcon loader honors /usr/share/pixmaps
              directory.  This is a valid directory per the Freedesktop.org
              icon theme specification.
 Bug: https://bugreports.qt.nokia.com/browse/QTBUG-12874

Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
Get and set XDG user dirs variables in config file

Config file set in $XDG_CONFIG_HOME/user-dirs.dirs.
Merge branch 'use-qt5-qiconloader'

* use-qt5-qiconloader:
  Honors /usr/share/pixmaps when searching for icons.
  Adds xpm icon support
  Adds Qt5 QIconLoader for the Qt5 build
Fixes an FTBFS in the Qt4 build

Change-Id: Ic0d6448355be6c94fb36bd134fdfb36b25790c88
Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
Revert "Fixes an FTBFS in the Qt4 build"

This reverts commit bd9510f926aeb7bbdb11b428ab2c26e82861be37.
Revert "Merge branch 'use-qt5-qiconloader'"

This reverts commit b18046858e4911c58de1dbfd57e8177bdd65ae0b, reversing
changes made to 0d80985769ab05691ab3c8768ca63f7b6c74feb4.
Merge branch 'use-qt5-qiconloader'

* use-qt5-qiconloader:
  Honors /usr/share/pixmaps when searching for icons.
  Adds xpm icon support
  Adds Qt5 QIconLoader for the Qt5 build

(cherry picked from commit b18046858e4911c58de1dbfd57e8177bdd65ae0b)
Fixes an FTBFS in the Qt4 build

Change-Id: Ic0d6448355be6c94fb36bd134fdfb36b25790c88
Signed-off-by: Luís Pereira <luis.artur.pereira@gmail.com>
(cherry picked from commit bd9510f926aeb7bbdb11b428ab2c26e82861be37)
Allows QIconLoader to search in multiple theme directories.

Even when QIcon::themeSearchPaths() returns a list QIconLoader doesn't
honor it. It will search for an icon in the first directory it finds (that
has the current theme).
QIcon still doesn't support a theme that is spread across several
directories. And it's a fundamental feature needed to support user
installed icons, e.g., the hicolor theme.