LibOverride: Add Pointer properties to 'overridable by default'.

There is in fact no reason not to do so, RNA pointers are either to
other IDs (which is properly handled by default diffing code), or to
sub-structures that should almost always  be diffed as well.

Exceptions (like backward ID pointers or strictly runtime caches and
data) are to be handled with proper 'no comparison' flag in any case.

source/blender/makesrna/intern/rna_define.c

@@ -1425,10 +1425,8 @@ PropertyRNA *RNA_def_property(StructOrFunctionRNA *cont_,
   }
 
 #ifndef RNA_RUNTIME
-  if (type != PROP_POINTER) {
-    if (DefRNA.make_overridable) {
-      prop->flag_override |= PROPOVERRIDE_OVERRIDABLE_LIBRARY;
-    }
+  if (DefRNA.make_overridable) {
+    prop->flag_override |= PROPOVERRIDE_OVERRIDABLE_LIBRARY;
   }
 #endif