simplify shadowing notes non-trivial localparams too

test/basic/simplify_localparam_shadow.sv

@@ -0,0 +1,10 @@
+module top;
+    localparam i = 1234;
+    if (1) begin
+        genvar j;
+        for (j = 0; j < 10; j = j + 1) begin
+            localparam i = j;
+            initial $display(i > 5 ? i + 100 : i - 100);
+        end
+    end
+endmodule