Update for paraview 5.4.0 (#4582)

- paraview 5.2.1 -> 5.4.0 supports both Qt4 and Qt5, but the assumed
  default version changes between versions. So explicitly define
  which QT major version is being used.

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

@@ -33,6 +33,7 @@ class Paraview(CMakePackage):
     url      = "http://www.paraview.org/files/v5.3/ParaView-v5.3.0.tar.gz"
     _urlfmt  = 'http://www.paraview.org/files/v{0}/ParaView-v{1}{2}.tar.gz'
 
+    version('5.4.0', 'b92847605bac9036414b644f33cb7163')
     version('5.3.0', '68fbbbe733aa607ec13d1db1ab5eba71')
     version('5.2.0', '4570d1a2a183026adb65b73c7125b8b0')
     version('5.1.2', '44fb32fc8988fcdfbc216c9e40c3e925')
@@ -117,6 +118,13 @@ def nvariant_bool(feature):
             '-DVTK_USE_SYSTEM_ZLIB:BOOL=ON',
         ]
 
+        # The assumed qt version changed to QT5 (as of paraview 5.2.1),
+        # so explicitly specify which QT major version is actually being used
+        if '+qt' in spec:
+            cmake_args.extend([
+                '-DPARAVIEW_QT_VERSION=%s' % spec['qt'].version[0],
+            ])
+
         if '+python' in spec:
             cmake_args.extend([
                 '-DPARAVIEW_ENABLE_PYTHON:BOOL=ON',