[cs] force problematic Vector methods to be removed

std/haxe/ds/Vector.hx

@@ -227,7 +227,7 @@ abstract Vector<T>(VectorData<T>) {
 		`a[i] == a.copy()[i]` is true for any valid `i`. However,
 		`a == a.copy()` is always false.
 	**/
-	public inline function copy<T>():Vector<T> {
+	#if cs @:extern #end public inline function copy<T>():Vector<T> {
 		var r = new Vector<T>(length);
 		Vector.blit(cast this, 0, r, 0, length);
 		return r;
@@ -246,7 +246,7 @@ abstract Vector<T>(VectorData<T>) {
 
 		If `sep` is null, the result is unspecified.
 	**/
-	public inline function join<T>(sep:String):String {
+	#if cs @:extern #end public inline function join<T>(sep:String):String {
 		#if (flash||cpp)
 		return this.join(sep);
 		#else