This is a prerequisite for building the bundled 3rd party libraries.
Because the feature evaluation will be moved into src/CMakeLists.txt,
some of the X11 packages were found in the src dir, and then a second
time inside the x11-related projects.
These qt_find_package calls in the x11 related projects tried to
promote the imported targets to global, which failed, because they were
created in a different directory scope.
To avoid this, the special case qt_find_package calls are removed from
the nested projects.
Also, fix the mapping of some of the x11 libraries to be correct
- xkbcommon_x11 was incorrectly mapped to XKB::XKB instead of the
xkb common x11 library
- xlib was mapped to xcb, whereas X11 is the correct CMake target
Change-Id: I30781b2ecbdd478c98419b14baa0492037e49c61
Reviewed-by: Leander Beernaert <leander.beernaert@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>