Multi-declarations supported in all flavours of for loops

(KT-2635 Support iteration with multiple range variable in JVM back-end)
 #KT-2635 Fixed

compiler/testData/codegen/multiDecl/forRange/MultiDeclForComponentExtensions.kt

@@ -0,0 +1,34 @@
+class Range(val from : C, val to: C) {
+    fun iterator() = It(from, to)
+}
+
+class It(val from: C, val to: C) {
+    var c = from.i
+
+    fun next(): C {
+        val next = C(c)
+        c++
+        return next
+    }
+
+    fun hasNext(): Boolean = c <= to.i
+}
+
+class C(val i : Int) {
+    fun rangeTo(c: C) = Range(this, c)
+}
+fun C.component1() = i + 1
+fun C.component2() = i + 2
+
+fun doTest(): String {
+    var s = ""
+    for ((a, b) in C(0)..C(2)) {
+        s += "$a:$b;"
+    }
+    return s
+}
+
+fun box(): String {
+    val s = doTest()
+    return if (s == "1:2;2:3;3:4;") "OK" else "fail: $s"
+}