fix qt@5.8: build on systems without wayland (#8417)

* fix qt@5.8: build on systems without wayland

Change-Id: I56b83208edd46f50e003d82c071e296e905bfb15

* add links

Change-Id: Ia16fc20632690340f33df77fbdcb1a166d49cedc

* move 5.8 comparison into 5.7 configure block

Change-Id: I7dc606beeb5b5bf4e8263bc50d28de6591633c99

var/spack/repos/builtin/packages/qt/package.py

@@ -378,6 +378,12 @@ def configure(self):
                 '-skip', 'webglplugin',
             ])
 
+        if self.version > Version('5.8'):
+            # relies on a system installed wayland, i.e. no spack package yet
+            # https://wayland.freedesktop.org/ubuntu16.04.html
+            # https://wiki.qt.io/QtWayland
+            config_args.extend(['-skip', 'wayland'])
+
         configure('-no-eglfs',
                   '-no-directfb',
                   '-{0}gtk'.format('' if '+gtk' in self.spec else 'no-'),