Revert "Disable desktop settings awareness for now"

This reverts commit 10652f8dd675aa0d12c11597c165831c8ba0b8b4 which
disabled desktop settings awareness to avoid loading themes for X11.

However, Hawaii is a Wayland-only desktop environment and only the
themes shipped with Qt are provided by Maui. Disabling desktop
settings awareness will not load icon themes making the DE unusable.

Conflicts:
	src/plugins/platforms/wayland_common/qwaylandintegration.cpp
Fix the popups handling.

Use wl_shell_surface_set_popup() instead of wl_shell_surface_set_transient(),
since the latter is not supposed to make the surface follow the transient
parent movements.

Needs Weston master or 1.0.6, otherwise freezes will happen.
To have the best experience you should however use recent weston master.
The popups in QtCompositor are badly placed.

Change-Id: I3c86e5d74503514749840681b4e81c58cd73ca70

Conflicts:
	src/plugins/platforms/wayland_common/qwaylandshellsurface.cpp
	src/plugins/platforms/wayland_common/qwaylandwindow.cpp
	src/plugins/platforms/wayland_common/qwaylandwindow.h
Attach always the front buffer before committing it.

The attach semantics changed in Wayland master.

Change-Id: I79efa5e3b2d048604cadb18543101a869ccb6835
Fix qtwaylandscanner build

Header doesn't exist.

Change-Id: I15f33e667382f7adca3c85bc874f3e88c73f6083