Made vararg parameters have Array<out T> type

instead of simply Array<T>
  #KT-1638 Fixed
  #KT-2163 Fixed
  #KT-3213 Fixed
  #KT-4172 Fixed
  #KT-5534 Fixed

compiler/testData/diagnostics/tests/varargs/varargsAndOut1.kt

@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+fun test(vararg a: String) {
+    a checkType { it : _<Array<out String>> }
+
+    foo(a) checkType { it : _<Array<out String>> }
+}
+
+fun <T> test1(vararg t: T) {
+    t checkType { it : _<Array<out T>> }
+}
+
+fun <T> foo(a: Array<T>): Array<T> = a