Fix T79992: Error calling context.copy() in Properties Editor

This was an oversight in rB83e3d25bcae3.

Basically we still have the "hair" and "point_cloud" entries for the
context. However they were ifdef'ed.

Note this would mostly happen in 2.90 since we always build without hair
and particles there.

Differential Revision: https://developer.blender.org/D8712

source/blender/editors/space_buttons/buttons_context.c

@@ -795,8 +795,12 @@ const char *buttons_context_dir[] = {
     "line_style",
     "collection",
     "gpencil",
+#ifdef WITH_HAIR_NODES
     "hair",
+#endif
+#ifdef WITH_PARTICLE_NODES
     "pointcloud",
+#endif
     "volume",
     NULL,
 };