[build] Remove the AC_DEFINE for glade, not needed
[build] Remove the AC_DEFINE for glade, not needed

The glade support doesn't actually change anything in terms of building,
so don't bother having a define for it - it's unnecessary (for now).

pwithnall/mx,jonnylamb/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,clutter-project/mx