Added support for hierarchical defparams

tests/simple/hierdefparam.v

@@ -0,0 +1,23 @@
+module hierdefparam_top(input [7:0] A, output [7:0] Y);
+  generate begin:foo
+    hierdefparam_a mod_a(.A(A), .Y(Y));
+  end endgenerate
+  defparam foo.mod_a.bar[0].mod_b.addvalue = 42;
+  defparam foo.mod_a.bar[1].mod_b.addvalue = 43;
+endmodule
+
+module hierdefparam_a(input [7:0] A, output [7:0] Y);
+  genvar i;
+  generate
+    for (i = 0; i < 2; i=i+1) begin:bar
+      wire [7:0] a, y;
+      hierdefparam_b mod_b(.A(a), .Y(y));
+    end
+  endgenerate
+  assign bar[0].a = A, bar[1].a = bar[0].y, Y = bar[1].y;
+endmodule
+
+module hierdefparam_b(input [7:0] A, output [7:0] Y);
+  parameter [7:0] addvalue = 44;
+  assign Y = A + addvalue;
+endmodule