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/testsWithStdLib/varargs/kt3213.kt

@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+
+fun test(a: Array<out String>) {
+    val b = a.toList()
+
+    b checkType { it : _<List<String>> }
+}