KT-2632 Check multi-declaraions in for-loops

#KT-2632 Fixed

compiler/testData/diagnostics/tests/declarationChecks/multiDeclarations/ForLoopWithExtensions.kt

@@ -0,0 +1,14 @@
+class A {
+}
+fun A.component1() = 1
+fun A.component2() = 1
+
+class C {
+    fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, y) in C()) {
+
+    }
+}