Allow initialization of static/global variables with the address of members of const structs.

Note that this code currently permits discarding the const qualifier via such an initialization. That should give a diagnostic, but currently it doesn't in this or various other cases.

The following code (derived from a csmith-generated test case) illustrates the problem:

struct S0 {
   const long  f4;
};
const struct S0 g_149;
const long *g_311 = &g_149.f4;

Parser.pas

@@ -1844,6 +1844,8 @@ var
          end {if}
       else if tree^.token.kind = dotch then begin
          tp := Subscript(tree^.left);
+         while tp^.kind = definedType do
+            tp := tp^.dType;
          if tp^.kind in [structType,unionType] then begin
             DoSelection(tp, tree^.right, select);
             Subscript := expressionType;