Support overloaded functions

[Toshiaki Kameyama]

class Foo(val x: Int, y: Int, z: Int) {
    constructor(x: String, y: String) : this(x.length, y.length, x.length + y.length)
}

fun bar(x: Int, y: Int, z: Int) {}
fun bar(x: String, y: String) {}

fun main() {
    Foo()
    bar()
}