Don't rely on deprecated annotation to declare extern fields (#1170)

hxd/res/FileTree.hx

@@ -279,8 +279,8 @@ class FileTree {
 					ret : field.t,
 					expr : { expr : EMeta({ name : ":privateAccess", params : [], pos : pos }, { expr : EReturn(field.e), pos : pos }), pos : pos },
 				}),
-				meta : [ { name:":extern", pos:pos, params:[] } ],
-				access : [AStatic, AInline, APrivate],
+				meta : [],
+				access : [AExtern, AStatic, AInline, APrivate],
 			};
 			var field : Field = {
 				name : fname,