build: Look for mutter-clutter-4 if 3 is not found.

meson.build

@@ -51,6 +51,10 @@ xdo_lib = cc.find_library('xdo', dirs : ['/usr/lib'], required : false)
 
 mutter_clutter_dep = dependency('mutter-clutter-3', required : false)
 
+if not mutter_clutter_dep.found()
+  mutter_clutter_dep = dependency('mutter-clutter-4', required : false)
+endif
+
 subdir('src')
 subdir('examples')
 subdir('tests')