cleanup some circular dependencies

std/python/_std/Math.hx

@@ -303,7 +303,7 @@ extern class Math
 		NEGATIVE_INFINITY = __python__("float")('-inf');
 		POSITIVE_INFINITY = __python__("float")('inf');
 		NaN = __python__("float")('nan');
-		PI = Reflect.field(Math, "pi");
+		PI = untyped __python__("_hx_math.pi");
 	}
 
 }

std/python/_std/Std.hx

@@ -92,7 +92,7 @@ import python.Boot;
 
             function loop (intf)
             {
-                var f:Array<Dynamic> = Reflect.field(intf, "_hx_interfaces");
+                var f:Array<Dynamic> = if (Builtin.hasattr(intf,"_hx_interfaces")) Builtin.getattr(intf, "_hx_interfaces") else [];
                 if (f != null) {
                     for (i in f) {
                         if ( i == t) {